This article lists the most common ailments in community tank fishes. It will make it easy for you to identify issues in your fish collection and take necessary actions in a timely manner.

Basics

Early detection and cure go a long way in saving your fish.

While many of the diseases are curable, if they are not detected and treated in the early stages, they can prove fatal and might even impact other tank mates adversely.

A few of them are not detectable until they reach advanced stages (like dropsy).

Always quarantine the infected fish in a hospital tank (separate/temporary) tank.

This will stop the disease from spreading, reduce stress factors, and enable closer monitoring of the fish during treatment.

Avoid using medication(s) containing any ingredient(s) known to be toxic to specific fish (like sea stars are toxic to copper-based or anti-parasitic medications)

It’s recommended that you consult a fish vet for proper diagnosis and treatment. It is always better to consult them for choosing and administering any over-the-counter medicine.

When administering over-the-counter medicines, use only half the recommended dose for scaleless fish, fish with tiny scales, or fish-eels (like Yoyo Loaches, Kuhli Loaches, Tire Track Eels, etc.)  as they are highly sensitive to medications.

Types of Fish Diseases and Names of Common Diseases in Each Type

A. Common Bacterial Diseases in Fish
Freshwater Fishes Both (Freshwater and Marine Fishes) Saltwater/Marine Fishes

Cotton Mouth/Columnaris / Cotton Wool/Saddle back / Guppy/ Flexibacter / False Neon Disease

Red Pest

  • Fish Tuberculosis
  • Dropsy (Goldfish are highly prone)
  • Furunculosis (mostly in Salmonids)
  • Fish Vibriosis
  • Fin Rot/Tail Rot (caused by bacteria and Fungus)
None
B. Common Fungal Diseases in Fish
(Opportunistic as it targets fish with weaker immunity)
Freshwater Fishes Both (Freshwater and Marine Fishes) Saltwater/Marine Fishes

Body Fungus/Saprolegniasis

Branchiomycosis/Gill Rot (also infects brackish water fishes)

Dermatomycosis

  • Ichthyosporidium
  • Fin Rot/Tail Rot (caused by bacteria and Fungus)
None
C. Common Viral Diseases in Fish
Freshwater Fishes Both (Freshwater and Marine Fishes) Saltwater/Marine Fishes

None

Lymphocystis

None
D. Common Parasitic Diseases in Fish
Freshwater Fishes Both (Freshwater and Marine Fishes) Saltwater/Marine Fishes

Velvet/Rust/Gold Dust Disease*

Leeches

Flukes

Nematoda / Nematodes / Roundworms

Anchor Worm

Ergasilus / Gill Lice

Fish Louse / Argulus/Common Fish Louse / Fish Lice

Black Spot / Black Ick / Diplopstomiasis

Marine Velvet Disease*

Marine Leeches (rare)

E. Common Protozoan Diseases in Fish
Freshwater Fishes Both (Freshwater and Marine Fishes) Saltwater/Marine Fishes

Ich / Ick / White Spot Disease / Ichthyophthirius Multifiliis

Tetrahymena Pyriformis / Uronema in Freshwater

Ichthyobodosis / Costiasis / Costia

Neon Tetra Disease (first found in Neon Tetra fish)

Salmonoid Whirling Disease / Whirling Disease

Hexamitiasis / Hexamita

Marine Ich / Crypt / Marine White Spot Disease / Cryptocaryon Irritans

Uronema Marinum / Scuticociliatosis / Scutica infection

Ichthyobodosis in Marine Fish

Brooklynellosis / Clownfish Disease

F. Common Protozoan Diseases in Fish
Freshwater Fishes Both (Freshwater and Marine Fishes) Saltwater/Marine Fishes

Red-spot Disease / Epizootic Ulcerative Syndrome (EUS) / Mycotic Granulomatoses (MG) / (impacts brackish water fishes too)

Swim Bladder Disease

Hole-In-The-Head (HITH)/ Head and Lateral Line Erosion (HLLE)

Scoliosis/Bent Spine

Pop-eye (Exophtalmia) / Other eye problems

Skinny/Wasting

None

Details of all Common Diseases in Fish

The following table gives details of each disease as follows:

See also  Is Your Fish Tank Water Suddenly Green: Ways to Control Algae Bloom

Name/Type – Popular names/ Contagious, fatal, etc.

Causes – Possible causes

Symptoms – Possible symptoms

Basic Treatment – Basic steps in treatment

Table A – Common Bacterial Diseases in Fish
Name/Type Causes Symptoms Basic Treatment

Fish Tuberculosis
Piscine Tuberculosis
Acid-fast Disease
Granuloma Disease

Contagious, Maybe fatal

Can be passed from fish to humans

Adding a TB carrier fish or

Adding infected items in the tank (plants, decor, etc. (which have the bacteria)

Loss of appetite

Lazy/laid back

Fin/Tail rot, clamped fins

Lesions or ulcers on body

Skinny appearance, hollow belly

Loss of scales, color, Skeletal deformity (like a bent spine)

Prefers to hide in the tank (unusual behavior)

Isolate the affected fish carefully (it can infect  you), into a hospital tank

Nutritional diet quality to boost immunity

Administer strong antibiotics for TB (2 different medications for at least 3 months

Consult a vet before concluding

Clean the main tank thoroughly and maintain the quality of tank water and the environment consistently

Observe tank mates for infection

Cotton Mouth
Columnaris
Cotton Wool
Mouth Fungus
Saddle Back
Guppy Disease
Flexibacter
False Neon Disease

Highly Contagious, Difficult to treat

External or internal infection due to bacteria entering the body
Poor tank water quality

Contaminated material entering the tank

Environmental stress (handling, transportation, tank mates, overcrowding, etc.)

Poor diet

Wound

Gray or white lining around the mouth which slowly develops into cotton-like fungus

Excess mucus near the gills

Loss of appetite

Random scratches on the body

White spots near the mouth, fins, scales

Ulcer(s) on the body (advanced stages)

Thin, wire-like poop might be observed

 

Isolate the affected fish into a quarantine tank

Add aquarium salt

Both tank water tank parameters should be fixed after cleaning them thoroughly. Maintain them consistently

Nutritional diet to strengthen immunity

Consult a vet for complete treatment

Treat with a gram-negative medication for Columnaris

If it’s a similar disease but not Columnaris, gram-positive medication will show results

If unsure, use both – gram-negative and positive medications

Administer antibiotics

Use medicated food to heal internal infection

Observe tank mates for health issues

Dropsy

Contagious, mostly fatal

Bacterial Infection impairs kidney function, causing water retention in the body

Poor tank water quality

Contaminated material entering the tank

Environmental stress (handling, transportation, tank mates, overcrowding, etc.)

Poor diet

Swollen belly despite normal feeding and not pregnant

Protruding scales

Bulging eyes

Weird swimming, Pale body, pale feces, swollen/red anus, and curved spine, etc. might be observed

Isolate affected fish into a separate tank

Maintain a low enough water-level in the quarantine tank for the fish to breathe easily from top
Add a tablespoon of salt per gallon of water
Use a broad-spectrum antibiotic to fight a variety of bacteria (both gram-positive and gram-negative)
Administer over-the-counter medicine
Consult a vet along with the above
Fix both the tank water parameters after cleaning them thoroughly and keep them optimal

Observe tank mates for infection

Furunculosis

Contagious, mostly fatal

Almost similar to Fish Vibriosis, but caused by a different bacteria (A. salmonicida)

Bacteria enters the tank through any infected fish/object

Enters through food (eating infected fish) or open wounds

Blood/red colored boils on the body and in reproductive and digestive organs, with bloody discharge

Bulging eyes

Loss of appetite

Breathing issues. Might jump a lot to get oxygen

Lazy/laid back and remains at the bottom

Darker body, pale gills

Mucus in the stomach

Isolate affected fish into a quarantine tank

Administer antibiotics

Consult a vet at the earliest

Use vaccination proactively

Clean both the tanks thoroughly. Fix and maintain the tank water parameters consistently

Observe, if tank mates for health issues

Fish Vibriosis
Fish Handler’s Disease
Aquarium Handler’s Disease

Contagious, mostly fatal

Can be passed from fish to humans

 Almost similar to Furunculosis but caused by a different bacteria  (V. salmonicida, V. Anguillarum, V. Ordalii, V. Damsela)
Enters through food (eating infected fish) or open wounds

Bacteria enters the tank through any infected fish/object

Skin hemorrhage
Loss of appetite

Breathing issues. Might jump a lot to get oxygen

Lazy/laid back and remains at the bottom

Isolate the affected fish carefully (it can infect  you), into a hospital tank

Administer antibiotics

Consult a vet at the earliest

Use vaccination proactively

Fix both the tank water parameters after cleaning them thoroughly and keep them optimal

Observe tank mates for infection

Fin Rot/Tail Rot

Contagious

Bacteria/Fungus, or both at the same time

Poor tank environment

Environmental stress (handling, transportation, aggressive  tank mates, overcrowding, etc.)

Infection through wound

Ragged fins/tails (shredding, stuck, deformed, etc.)

Loss of tail/fin

Black, white, brown spots on fins and tails

Reddish skin near the fins or tails

Loss of appetite

Lethargic/inactive

Isolate affected fish into a quarantine tank

Consult a vet for proper diagnosis and treatment, as this can be caused by a variety of factors/diseases.

Change the tank water and maintain an optimal environment in both the tanks

Administer antibiotics through water/food

Observe tank mates for infection

Red Pest
HemorrhagicSepticemia
Septicemia

Not Contagious

Poor tank environment

Environmental stress (handling, transportation, aggressive  tank mates, overcrowding, etc.)

Poor diet, and anything leading to weak immunity

Red patches/ulcers on the body

In dark-colored fishes, a red patch is not easier to notice, but clamped fins and Increased mucus can be observed

Weird Swimming, Breathing issues, and Popping eye(s) may be observed

Can lead to other diseases, if not treated by fixing water parameters (a major culprit – 90%)

Isolate affected fish into a quarantine tank

Add 5 teaspoons of non-iodized salt/per gallon of water

Add over-the-counter medication for external bacterial infection

Clean both the tanks thoroughly. Fix and maintain the tank water parameters consistently

Feed a nutritional diet to improve immunity

Consult a vet

Scale Protrusion

Poor diet, and anything leading to weak immunity

 

Poor tank environment

Environmental stress (handling, transportation, aggressive  tank mates, overcrowding, etc.)

Protruding or conical scales without bloating (unlike dropsy)

 

Isolate affected fish into a hospital tank

Feed nutritional food to improve immunity

Administer antibiotics through food

Fix both the tank water parameters after cleaning them thoroughly and keep them optimal

Table B. Common Fungal Diseases in Fish
Name/Type Causes Symptoms Basic Treatment

Body Fungus
Saprolegniasis
Water Mould Diseases

 

Contagious, mostly fatal

A water fungus that reaches tank (and thus the fishes) through contaminated food or open wounds

Infected tank environment (affected food, fish, etc.)

Environmental stress (handling, transportation, aggressive tank mates, overcrowding, etc.)

Poor diet and anything leading to weak immunity

White to cotton-like patches on the body, fins, tails, or gills

Infected fish eggs turn white

Granuloma Lesions in internal organs might be observed

This might have infected more fish, but signs are not visible till advanced stages

Isolate affected fish into a hospital tank

Consult a vet at the earliest and administer over-the-counter medication, bath treatments, etc. as directed (including surgical removal of granuloma)

Identify and eradicate the cause of fungus in the tank environment

Disinfectify the main tank

Clean both the tanks thoroughly. Fix and maintain the tank water parameters consistently

Consider adding UV sterilizer to the tank

Nutritional feeding

Ichthyosporidium

Contagious, mostly fatal

Fungus invades kidney, liver, and internal organs

Infected tank environment (affected food, fish, etc.)

Environmental stress (handling, transportation, aggressive  tank mates, overcrowding, etc.)

Poor diet and anything leading to weak immunity

Loss of appetite

Erratic swimming (loss of balance)

Lazy/laid back/inactive

Shrunken belly

External lesions/cysts (advanced stages)

Isolate affected fish into a hospital tank

Consult a vet at the earliest and administer over-the-counter medication through water and food

Disinfectify the main tank

Fix both the tank water parameters after cleaning them thoroughly. Maintain them consistently

Nutritional diet

 

 

Branchiomycosis
Gill Rot

Contagious, mostly fatal

Poor fish tank management inducing fungal infection

Environmental stress (handling, transportation, aggressive  tank mates, overcrowding, etc.)

Poor diet and anything leading to weak immunity

Also infects brackish water fishes

Impacts blood circulation through the gills resulting in pale gills

Respiratory issues/ gasping for air on top of the tank

Loss of appetite/refuses to eat

 

 

 

Isolate affected fish into a quarantine tank

Consult a vet at the earliest for treatment

Disinfectify the main tank

Clean both the tanks thoroughly. Fix and maintain the tank water parameters consistently

Nutritional diet

Dermatomycosis

Contagious, mostly fatal

Poor fish tank management inducing fungal infection

Environmental stress (handling, transportation, aggressive  tank mates, overcrowding, etc.)

Poor diet and anything leading to weak immunity

Small hair-like suspension in the infected body part

The hair-like suspensions become bloody in advanced stages

Infected eggs stick to each other and die

 

Isolate affected fish into a hospital tank

Consult a vet at the earliest for treatment

Disinfectify the main tank

Fix both the tank water parameters after cleaning them thoroughly. Maintain them consistently

Nutritional diet

Table C. Common Viral Diseases in Fish
Name/Type Causes Symptoms Basic Treatment

Lymphocystis

Not contagious

 

Virus enters the tank through an infected fish addition or live food

 

 

Random cauliflower-like lumps on body resembling 

Breathing/mobility issues depending in the density of growth in various parts

 

 

Isolate affected fish into a hospital tank till it cures

There is no treatment unless it cures itself

Fix both the tank water parameters after cleaning them thoroughly and keep them optimal

Nutritional diet

Consult a vet

Observe other tank mates for infection if any

Table D. Common Parasitic Diseases in Fish

Name/Type

Causes

Symptoms

Basic Treatment

Velvet
Rust
Gold Dust Disease

Marine Velvet
Coral Reef Disease

Some classify it as a protozoan disease

Contagious, maybe fatal

 

Infected fish, food, plants, or decor added to the tank

Poor tank management induces parasites in the tank

Environmental stress (handling, transportation, aggressive tank mates, overcrowding, etc.)

Poor diet or anything lowering immunity gets the fish infected

Parasite multiplies in the tank and starts infecting more and more fish, if not checked

 

Thin yellow/light brownish layer on the skin as the parasite hosts  the skin/gills

The parasite drops on the plants etc. after some time and multiplies

Rubbing/scratching against hard surfaces in the tank due to itching

Lethargic

Fallen Fins resting on the abdomen

Skin peeling (advanced stages)

Breathing issues

Loss of appetite

Isolate affected fish into a separate tank

Dim the tank light to prevent the parasite from multiplying (using photosynthesis)

Increase the water temperature (of separate tank)

Use over-the-counter medication

Consult a vet

Disinfect the tank decor

Fix both the tank water parameters after cleaning them thoroughly and maintain them consistently

Observe other tank mates for infection

Flukes
Gill Flukes
Skin Flukes

 

Flatworms drill into the gills or skin (not visible to the naked eye)

These holes can result in other infections

Droopy/clamped fins

Excess mucus covering the skin/gills

Loss of appetite

Breathing issues

Gills look chewed/inflamed skin/hollow belly might be observed

Isolate affected fish into a hospital tank

Disinfect the tank decor

Clean both the tanks thoroughly. Fix and maintain the tank water parameters consistently

Use over-the-counter medication for anti-worming

Consult a vet

Nematoda
Nematodes
Roundworms

Contagious, may be fatal in later stages

Worms can be seen hanging out of the anus

Sunken belly (in extreme cases)

Loss of appetite

Laidback/inactive

Erratic swimming

Isolate affected fish into a quarantine tank

Sterilize the tank and decor

Clean both the tanks thoroughly. Fix and maintain the tank water parameters consistently

Consult a vet

Use over-the-counter medication through bath or food

Leeches
Marine Leech (rarely found)

Contagious, may be fatal in later stages

Curled leeches are seen anywhere on the body

They suck blood on their skin/other parts

Lethargic

 

Isolate affected fish into a quarantine tank

Consult a vet as it involves bathing the fish in salt solution and/or detaching the sucker leech with forceps without hurting the fish

Disinfect the tank decor

Fix both the tank water parameters after cleaning them thoroughly and maintain them consistently

Anchor Worm
Contagious, may be fatal in later stages

 

Anchor worms latch into the fish’s flesh

Rest of the white worm’s body can be seen hanging outside the fish body

Leave ugly holes of they die after leaving eggs in the fish, which can cause further complications, if not treated

 

Inflamed skin near the anchored area(s)

Scratching against hard surfaces in the tank

Isolate affected fish into a hospital tank

Consult a vet as it involves bathing the fish in medicated solution and/or detaching the worm(s) without hurting the fish

Sterilize the tank decor

Fix both the tank water parameters after thorough cleaning and keep them optimal

Ergasilus
Gill Lice

Contagious, may be fatal in later stages

Similar to Anchor worm, but smaller in size and hook to the gills only

Rest of the worm’s body can be seen hanging outside the gills

Scratching against hard surfaces in the tank

 

Isolate affected fish into a separate tank

Consult a vet as it involves bathing the fish in medicated solution and/or detaching the worm(s) without hurting the fish

Disinfect the tank and decor

Clean both the tanks thoroughly. Fix and maintain the tank water parameters consistently

Fish louse
Argulus
Common Fish Louse
Fish Lice

Contagious

Visible flat bug on the fish body

Scratching against hard surfaces in the tank

Droopy/clamped fins

Irritated/red skin around the bug

Isolate affected fish into a quarantine tank

Consult a vet as it involves bathing the fish in medicated solution and/or detaching the lice without hurting the fish

Sterilize the tank and decor

Fix both the tank water parameters after cleaning them thoroughly. Maintain them consistently

Black Spot
Black Ick
Diplopstomiasis

Contagious

Small black dots/spots on the body and around the mouth

Scratching against hard surfaces in the tank
Inflamed skin

Restless/stressed fish

Isolate affected fish into a hospital tank

Consult a vet

Administer salt baths and over-the-counter medicines as directed

Disinfect the tank and decor

Fix both the tank water parameters after a thorough cleaning and maintain them consistently

Table E. Common Protozoan Diseases in Fish

Name/Type

Causes

Symptoms

Basic Treatment

Ich
Ick
White Spot Disease
Ichthyophthirius Multifiliis

Marine Ich / Crypt /
Marine White Spot Diseas e/
CryptocaryonIrritans

Contagious, maybe fatal

Infected fish, plants, or decor added to the tank

Infected equipment used in tanks

Poor tank management induces parasites in the tank

Temperature changes

Environmental stress (handling, transportation, aggressive  tank mates, overcrowding, etc.)

Poor diet or anything lowering immunity gets the fish infected

Parasite multiplies in the tank and starts infecting more and more fish, if not checked

White Spots or group of such spots on the skin/fins

Breathing difficulty as the gills get affected

Scratching against hard surfaces in the tank

Droopy/clamped fins

Excessive mucus

Loss of appetite

Laidback/inactive, bloody scratches (advanced stages)

 

Isolate in a quarantine tank

Treatment depends on the life cycle phase of parasite viz. free swimming, cyst, or adult phase)

It’s easiest if detected in free swimming phase using chemical treatment

Consult a vet

Increase the water temperature

Add aquarium salt (as directed by vet)

Use over-the-counter medication

Disinfect the tank and decor

Clean both the tanks thoroughly. Fix and maintain the tank water parameters consistently

Observe other tank mates for health issues

TetrahymenaPyriformis(Uronema in Freshwater)

Uronema Marinum
Scuticociliatosis
Scutica Infection

Contagious, Maybe fatal

 

 

Same as above

Scratching against hard surfaces in the tank

Ulcers on the body

Droopy/clamped fins

Breathing issues

Loss of color

Dehydration

Excessive mucus

Loss of appetite

Large wounds (advanced stages)

Isolate in a hospital tank

Consult a vet

Use over-the-counter medication, antibiotic,

Freshwater bath (for marine fishes), as directed

Disinfect the tank and decor

Fix both the tank water parameters after cleaning them thoroughly. Maintain them consistently

Observe other tank mates for infection

 

 

Ichthyobodosis
Costiasis
Costia

Ichthyobodosis in Marine Fish

Contagious

 

 

 

The skin turns misty/frosted/milky

Laidback/inactive

Scratching against hard surfaces in the tank

Breathing issues

Excess mucus

Bluish-gray layer on the skin (advances stages)

 

Isolate in a quarantine tank

Consult a vet

Increase the water temperature

Use over-the-counter medication for Ick

Salt-water baths (for freshwater fishes as directed)

Sterilize the tank and decor

Clean both the tanks thoroughly. Fix and maintain the tank water parameters consistently

Observe other tank mates for health issues

SalmonidWhirling Disease
Whirling Disease

Contagious

 

The protozoan attacks head and spine

Swimming in whirly pattern

Structural deformity/dent in head

Black/darkened tail

Fatal as fish cannot swim or save itself from predators

Isolate in a separate tank

No known treatment. It will eventually die

Consult a vet

Disinfect the tank and decor

Fix both the tank water parameters after cleaning them thoroughly. Maintain them consistently

Observe other tank mates for infection

Brooklynellosis
Clownfish Disease

Contagious, Fatal

 

Loss of appetite

Scratches on the body

Excessive mucus

Scratching against hard surfaces in the tank

Breathing issues

Inactive/sluggish

Isolate in a hospital tank

Consult a vet

Sterlize the tank and its decor

Clean both the tanks thoroughly. Fix and maintain the tank water parameters consistently

Observe other tank mates for infection

Hexamitiasis
Hexamita

 

Contagious

This disease is caused by Protozoa and should not be confused with HeadIin-The-Hole or Head-Lateral-Line-Erosion, as they have different causes

The protozoa impact affects lower intestine

Thin, slimy excreta

Loss of appetite

Loss of weight

Hides in the corner

Thinning of the head skin

Darkened body color (advances stages)

Isolate in a hospital tank

Consult a vet

Treatment includes over-the-counter medication through water and food

Disinfect the tank and decor

Fix both the tank water parameters after a thorough cleaning and keep them optimal

Observe other tank mates for infection

Neon Tetra Disease

Contagious, Fatal

 

 

This is a degenerative disease caused by the protozoa

Infected fish get cysts, which break into spores and spread into the tank water.

Thus invading other fishs’ digestive tracts

Loss of bright color in any area of the body

Weird swimming

Whitened areas in the flesh

 

Isolate in a separate tank

Consult a vet

There is no cure and it spreads quickly

Sterilize the tank and its decor

Clean both the tanks thoroughly. Fix and maintain the tank water parameters consistently

Observe other tank mates for infection (chances are they might be already infected and meeta similar fate)

F. Common Miscellaneous Diseases in Fish

Name/Type

Causes

Symptoms

Basic Treatment

Red-spot Disease
Epizootic Ulcerative Syndrome (EUS)
MycoticGranulomatosis (MG)

Caused by a seasonal epidemic fungus called Aphanomycesinvadans

Affects fresh/brackish water fishes

Adding infected fish/plant to the aquarium

 

Red spot on the skin

Scratches on the skin lead to ulcers and tuffs

Formation of granulomas internally (advances stages)

Isolate in a quarantine tank

Consult a vet

There is no cure

Disinfect the tank and its decor

Fix water parameters for both tanks after cleaning them thoroughly. Maintain them consistently

Observe other tank mates for infection

Swim Bladder Disease

Not contagious,

Swim Bladder is caused due to:

Poor tank water quality

Environmental stress (handling, transportation, aggressive  tank mates, overcrowding, etc.)

High Ammonia level

 

Balance issues while swimming

Swimming or floating weirdly (upside down, sideways, etc.)

Bloated belly (though not pregnant or overfed)

Loss of appetite

Disorder may be temporary/permanent

Isolate the fish in a hospital tank with a lower water level to help it breathe easily

Consult a vet for proper diagnosis and treatment

Often cured

Fix both the tank water parameters after a thorough cleaning and keep them optimal

Observe other tank mates for symptoms

Hole-In-The-Head (HITH)
Head and Lateral Line Erosion (HLLE)

Not contagious in earlier stages

No specific cause

Poor tank management

Environmental stress (handling, transportation, aggressive  tank mates, overcrowding, etc.)

Poor diet or anything leading to reduced immunity

Even Hexamitiasis can cause holes in the body and head in advanced stages

Dents/pits in the head/face/lateral line which might result in other infections

Large cavities (advanced stages)

 

Isolate in a quarantine tank

Consult a vet for proper diagnosis and treatment

Nutritional diet

Fix both the tank water parameters after cleaning them thoroughly and keep them consistent

Look after other tank mates for health issues

Scoliosis
Bent Spine

Not contagious

Genetic or

Environmental stress (handling, transportation, aggressive  tank mates, overcrowding, etc.)

Poor diet, or anything leading to reduced immunity

Curved back/spine

Swimming issues (due to crooked spine)

Isolate and prevent them from mating till the cause is diagnosed and fixed

Consult a vet

 

Pop-eye (Exophtalmia)
Other eye problems

Not likely to be contagious

Due to bacteria, fungus, or other diseases

Environmental stress (handling, transportation, aggressive  tank mates, overcrowding, etc.)

Vitamin deficiency

Inappropriate aquarium lighting

Poor diet

 

Eye(s) look bulging or out of the eye socket

Swelling

Blindness

Misty/opaque cornea

Isolate the infected fish

Consult a vet to identify the cause and treatment

Nutritional diet

Fixing stress factors in the tank (including tank lighting)

 

Skinny/Wasting
Maybe contagious if unchecked

Internal Parasites, or

Environmental stress (handling, transportation, aggressive  tank mates, overcrowding, etc.)

Poor diet

 

Unexplained weight loss despite proper eating

 

Isolate in a quarantine tank

Treatment will vary according to the root cause

Consult a vet for proper diagnosis and treatment

Nutritional diet

 

Ammonia/Nitrate Poisoning

Can be fatal

High level of Ammonia or Nitrate due to

New tanks, with incomplete/no nitrogen cycling

Poor tank management

Overfeeding (leading to uneaten waste rotting in the bottom)

 

 

 

Laid back/inactive

Fading color

Loss of appetite

Breathing issues

Swimming issues

Dis-oriented in the tank

Brown/purple/bleeding gills

Droopy/ragged fins

Eye problems

Curved spine

Ensure to complete a nitrogen cycle in the new tank before adding the fishes

Close monitoring after fixing

Maintain optimal tank environment

Nutritional food. Don’t overfeed

Break the tank before adding fish to a new aquarium

Prevention

The root causes of any disease are a poor tank environment, stress, overfeeding, or malnutrition. Keep these in check and your fishes will thank you.

 Simple steps to ensure happy and healthy fishes are listed below.

General Factors

  • Acclimatethe fishes before adding them to the aquarium.
  • Ensure the nitrogen cycle is completed or the tank is broken if using a new fish tank.
  • Everything in the tank should have rounded corners.
  • Enough space between all decor for all tank-dwellers to swim through.
  • Apt tank size, decor, lighting, plants, etc.
  • Oxygen and Filtration
  • Maintain the required tank water parameters consistently (including periodic cleaning and water changes).
  • Give them a regular balanced diet. Avoid overfeeding.
  • Avoid overcrowding the tank.
  • Choose tank mates wisely (to avoid aggression, stress, wounds, etc. within tank mates).
  •  Ensure everything that goes into the tank is high quality and free of any bacteria/parasites (from water to decor, to fishes, to food)
  • Also read about Dropsy, and its preventive measures.

Red Flags

Physical Indicators

  • Unexplained weight gain/loss.
  • Unexplained change in appetite.
  • Spots, wounds, holes, damaged body parts.
  • Unexplained color changes.
  • Weird swimming pattern.
  • Breathing issues – coming to the top level and gasping for air.

Stress Indicators

They can be observed in behavioral and some physical changes like

  • Inactive, lazy, and less active than usual.
  • Might even lay down in a cozy corner in the tank.
  • Swimming weirdly.
  • Gasping for air or breathlessness.
  • Choosing to hide in the tank decor to avoid particular tank mate(s).
  • Unexplained loss of appetite.
  • Unexplained weight loss

Conclusion

Maintaining proper hygiene and choosing your fish collection wisely with an apt tank decor is the key to happy tank-dwellers.

Hopefully, you are now empowered to keep your pet fishes healthy.

We wish your fish a speedy recovery and a happy fish-parenting time to you!

About the Author

Victoria Lamb

Victoria is a freshwater aquatics specialist, fish keeper, and amphibian enthusiast. She has had more than 6 years of experience caring for aquariums and keeping several fish species, and her home boasts of 3 aquariums and a garden pond. Her goal is to educate fish owners on raising healthy and happy aquatic pets.

Career Highlights:

  • Has worked with several aquarium manufacturers as a consultant
  • Organized and hosted workshops on freshwater fish keeping at retail stores, educational facilities, and libraries
  • Released content for the amphibian community through her writings

Educational Highlights:

Bachelor of Science in Animal Behavior and Welfare

  • University of Lincoln, Lincoln, UK (2014-2018)

Writing Experience

Victoria has done ghostwriting for many aquarium and pet websites in the past. She has also worked for Canada's largest natural health magazine- ALIVE, with 300,000 monthly circulations as a freelancer. She had six published articles on animal behavior and welfare during her graduation for her thesis.

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