Being a Fish grandparent is an undeniably fulfilling yet challenging experience.

Every hobbyist, aquarist, and commercial breeder will agree that there is something new to learn from every batch.

Support groups and experts can advise and guide you. However, there is a lot you will discover only by yourself.

It is because nobody understands your fish better than you.

Even within the same species, there are slight variations in their preferences due to genetic and environmental factors (during domestication) impacting them.

This article provides complete guidance on the best care practices for fish eggs and babies in the aquarium.

How do Fish have Babies?

As with human beings, so with the fish.

Healthy parents reproduce healthy eggs/babies. Avoid inbreeding (mating offsprings of the same parents, wherever possible).

Caring for the fish fry(s) begins with caring for the parents, much before they breed (or spawn).

Before you add any species of fish, know their life cycle thoroughly. Gather basic information necessary to parent them. It is available online/offline.

  • Their average life span, diet, habitat, and size.
  • Sexual dimorphism – how to identify a male and female fish.
  • By which size/age are they sexually mature?
  • How do they reproduce (spawning triggers, season, egg laying or live-bearing, etc.)?
  • Mating indicators – physical and behavioral.
  • Gestation period – post pregnancy.
  • How many offspring do they deliver per spawn, etc.?

This information can vary from species to species.

Explore in depth the world of fish spawning.

Ways to Plan Reproduction

If you want them to reproduce, add a few, keeping the male: female ratio in mind.

Add four to six of them (depending on your tank size) if you cannot differentiate their gender till they breed. At least one or two of them are likely to be female.

Some fishes are more convenient to breed in captivity than others. While a few have not bred in captivity to date.

Select your collection accordingly.

In a worst-case scenario, buy or exchange to get a female fish for your community tank. Many sell pregnant fish.

At times, you might need to pair them off in a special breeding tank and replicate the spawning triggers (like increasing the water temperature, salinity, pH value, etc.) to spawn them.

Many fishes (like Guppies, Mollies, Platys, Killifish, etc.) reproduce in the community tank effortlessly.

Now that the ground is ready, look out for their mating behavior like:

  • The male fish constantly chases his female counterpart.
  • The female fish looks fuller in the abdomen due to eggs, indicating she is ready to spawn.
  • Increased interaction between the male and female fish.
  • They might bicker while pairing.
  • They search for a cave/create bubble nests to lay eggs, etc.

Ways to Prevent Reproduction

If you do not want them to reproduce for any reason, add only a single-gender fish (if it is possible to identify their gender).

Male fish are better, as some female fish can reproduce single-handedly using stored sperm from their previous mating.

Ensure you do not add an already pregnant fish.

Avoid adding tank mates which might cross-breed.

Besides appearing weird, cross-breeds would be challenging to nurture due to no prior information about them as a species.

Unplanned Reproduction

What if scattered fisheggs or babies suddenly appear in thetank one fine day?


You can:

  • Still care for them, and either retain them or sell/exchange them for any other fish of your choice with a vendor or other hobbyists.
  • Move the eggs/fry(s) to a separate tank.

If you do not have a small tank ready, keep them in an open transparent bowl. Add some main aquarium water to it. Attach it on the top, inside the main tank, away from the adult fish.

Change the bowl of water partially every day.

Arrange for a nursery tank at the earliest.

  • Or leave them to their fate. Their survival instincts will decide their future.
  • Remember, unfertilized eggs can contaminate the tank water quality. Remove them.
  • The tank dwellers or the parent(s) might feast on the eggs/fry(s) most of the time.
  • Follow the steps in section 1.1 to avoid future reproduction.
  • The first option is better and human.

Keep reading about how to care for them (from section 2.1).

Identifying and Caring for a Pregnant Fish

An impregnated fish has a distinctly swollen belly.

Her abdomen skin is stretched and thinned out. You will be able to see her eggs/eyes of the fry(s) through her belly skin.

She might be less active and prefer to rest.

Feed a higher-nutrition and protein-rich diet. She needs extra energy to nurture the eggs/fry(s).

If she feels bothered by the tank mates, move the breeding pair (or only the female fish, if necessary) to a separate tank with proper filtration and maintain good tank water quality.

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If the mother fish feels stressed or unsafe, she might not spawn despite bearing eggs.

The gravid spot near the anal of a live-bearing fish will darken as she nears the delivery stage.

Track the gestation period to help her release the eggs/fry(s) safely.

Once you notice an impregnated fish, start planning for food and a nursery tank for the eggs/fish babies.

How to Protect Fish Eggs

A mother fish lays numerous eggs in every spawning.  Locating and transferring them to a separate tank can be a daunting task.

Many fishes lack parental instincts, while a few (like nest builders and mouth brooders) display outstanding care for their eggs/babies.

If the parent fish are caring for and protecting the eggs, do not separate them from the parents. Instead, move the other adult fish from the tank to a separate tank.

If the parents are not protective, they and other adult tank mates are a threat to the fish eggs in the main tank. Hence, move the eggs to a nursery tank at the earliest after spawning.

There are several ways to deal with this, depending on the type of egg-laying fish.

Find out more on breeding and protecting their eggs.

Egg Depositors and Scatters

Some fish species deposit their eggs on a leaf, rock, plant, or in caves for added safety. Hence, they are called egg depositors.

Many fish species scatter their eggs into the water directly. The eggs are sticky and stick to the plants, rocks, or other tank decorations.

  1. Create a breeding tank with a sterilized marble substrate. Move the breeding pair to this tank.

When the female fish releases eggs, they will slip into the gap between the marble substrate, outside the reach of the parent fish.

After spawning, transfer the parent fish to the main tank.

  • You can attach a net along the inside walls of the tank. This net has tiny spaces for the eggs to fall outside the net, keeping them away from the reach of adult fish.

You can remove the net to gather the eggs or remove adult fish from the main tank.

  • Use a spawning mop in the main tank to capture the eggs. It is made of synthetic yarn and resembles a dense plant.

Spawning mops are available in most fish stores (online/offline). Alternatively,  here is a simple DIY video to make them with readily available and reusable items.

Keep it afloat (by attaching it to a ping-pong ball or a cork), suspend it in the middle level of the tank wall (by anchoring it with a sucky cup), or stick it to the bottom (by anchoring it with a sucky cup/rock), depending on where the eggs are likely to be scattered in the tank.

If unsure, attach them at all levels.

The mother fish will release the eggs on these mops. Free-falling eggs will also sink and get entrapped in the mop(s).

Gently remove the mop(s) with the eggs and place it in a separate tank at the earliest.

  • Providing sufficient cave-like structures using clay pots or DIY/readymade breeding cones can help collect and separate the eggs of cave-spawning fish easily.

The following video provides brilliant ideas about preparing a separate breeding tank for egg-scattering fish.

Egg Burriers

A soft spongy soil substrate is apt to help egg-burying fish to bury their eggs.

You can transfer the entire peaty substrate with the eggs to a nursery tank.

Mouth Brooders and Nest Builders

Either parent holds the eggs, newly hatched fish, or both in their mouth, even if it means starving for a few days.

The fry(s) often come out and might return to either parent’s mouth to sleep or whenever they sense danger.

Similarly, nest builders gather their eggs inside the bubble nest and protect them vigilantly till they hatch.

Move the other adult fishes to a separate tank instead of separating the eggs and parents. A stressed parent fish can even swallow an entire lot of eggs/fry(s)/both in one go, killing all of them.

A few experts prefer to detach the eggs from their mouth and hatch them in a separate tank. Avoid this unless you have some experience.

How to Protect Newborn Frys

Livebearers directly give birth to tiny baby fishes called frys.

They give birth to fewer fry(s) compared to the numerous eggs released by egg-laying fishes. However, these fry(s) have better survival rates than newly hatched fish.

Just like eggs, newborn fry(s) need to be separated from adult fishes before they feast on them.

When the mother fish is ready to deliver fry(s), move her to a spawning tank.

The upper portion of this tank has a breeding trap attached to it, which hooks the mother fish. It has small holes or slits at the bottom.

The fry(s) automatically swim down through these tiny slits immediately after birth, to the lower portion.

Thus, the newborns separate safely from the mother fish.

A breeding trap can stress out the mother, hampering the safe release of the babies. So avoid moving the mother fish too early into a breeding trap.

Also, use bigger breeding traps, which provide more space for the mother fish.

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Once done, transfer the mother fish back to the main tank.

Setting up a Nursery Tank

Start setting up a nursery (or Fry) tank as soon as the fish is pregnant. The spawning tank (sans the breeding trap) and separate tanks referred to in sections 2.1 and 2.2 can become fry tanks with certain setups.

You will have enough time to break the nitrogen cycle (since pregnancy), which is vital to curb nitrogen and ammonia levels in the tank water.

In addition, some algae and microorganisms will be ready in the tank by the time you transfer the eggs/fry(s).

Use a small tank initially. The newly hatched fish or newborn fry(s) should be able to access food without too much swimming, which can tire them.

At the same time, they should have enough space to move freely.

Simultaneously, keep a slightly bigger grow-out tank ready to move them as they grow in size.

A nursery tank must:

  • Have a heater to maintain the required water temperature.
  • It is advisable to add some water from the main tank to the nursery tank.
  • Thus, the eggs or fry(s) will share the same water as their mother.
  • Water from a matured fish tank has microorganisms (not visible to the naked eye).
  • These microorganisms act as food for the fish fry(s).
  • A good filtration system keeps the tank water clean.
  • The filtration system should not suck the eggs or fry(s) in the pipe.
  • A sponge filter is best.
  • An airstone and an adjustable air pump to oxygenate the water.
  • Nursery tanks require daily water changes and maybe more (if need be), as even the slightest compromise in the water quality can prove fatal.
  • Add a plant. It will promote algae growth, provide hiding space, and improve oxygen levels in the tank water.

The following video about how to set up a fry tank can be helpful.

Hatching the Eggs

Maintain the required water temperature and other parameters in the fry tank consistently, with daily water changes (partially).

Adjust the air pump to release a gentle airflow. A strong current can damage the eggs.

Direct the airflow near the eggs (the spawning mop/spongy soil substrate, etc.), but not directly on them.

It will keep them aerated, avoiding chances of fungal growth around them.

Eggs that fertilize will look darker, whereas unfertilized eggs will look white.

Unfertilized eggs can contaminate the tank water and infect the fertilized eggs.

Hence, keep removing them from the tank at the earliest.

Research indicates that:

  • 90 percent of newly hatched fish do not survive in the wild due to natural factors (water currents, falling prey to predators, infection, etc.).
  • Further, only a few of them manage to survive till maturity in the wild.
  • The survival rate of newly hatched fishes with the best care is only 70 percent due to inherent, uncontrollable (physics-related) factors.

Do not worry if you have to remove many unfertilized eggs. Follow these instructions to the tee to rear a few fry(s) successfully.

Eggs can hatch anytime in three to seven days or earlier. You will notice tiny fry(s). They will not swim but wriggle within the protective shell.

Be prepared to feed them once they start swimming (maybe in the next 48 hours).

Difference between Newly Hatched Fish and Live born Frys

Newly Hatched Fish LivebornFrys
Mother fish are egg-laying Mother fish are livebearers
Few of the numerous eggs hatch Every liveborn fish is alive
They eat the egg yolk inside the egg sacs till they hatch They are miniatures of the parent fish and need external diet immediately after birth
All organs develop after birth Have slightly developed organs at the time of birth
Their mouths are too small to open and eat Have relatively bigger mouths
Need time before they start swimming Are swimming right from their birth
Need special foods to grow Can eat the same food as adult fish immediately after birth in smaller portions   Eat special fry foods too

How and What to Feed Baby Fish

The first two weeks are the most critical in their survival.

As mentioned earlier, you should start planning food for baby fry(s) once the mother fish is pregnant.

You can choose to buy good quality, ready-made fry foods from the stores or prepare some foods on your own.

Readymade fry foods are expensive.

Simple DIY foods are better. They save you a lot of dollars, besides assuring the quality.

They need to be fed five to six times a day, in small portions which can fit into their tiny mouths and digest in their tender bodies.

Feed smaller portions and direct them to the fry(s), as they cannot recognize it as edible food until they eat it once.

Do not overfeed, as uneaten food will gather in the tank bottom, impacting the tank water quality.

It is best to feed them for two to three minutes and wait till they eat it. You will need to be on top of this, as frys that do not eat will die.

The baby fish diet depends on the diet of the species (carnivorous, herbivorous, or omnivorous).

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There is a range of foods you can select.


These are a group of invisible microorganisms that thrive naturally in aquariums with plants. All Baby fishes eat them.

You can culture infusoria in a glass jar. Sterilize the jar.

Drop in a lettuce leaf and fill it with some water from the main fish tank (also called matured aquarium water).

Plant fragments stuck in the tank filter can also be used to culture infusoria.

Leave it open in a sunny spot for a week.

The water will turn cloudy initially. Stir it a little and wait for a few more days. The water will turn clear and then pinkish when infusoria is ready to use.

Take some water from the bottom and pour it into the fry tank.

The infusoria will live in the fry tank for the next 24 hours. Fry(s) can eat them as and when they are hungry.

Whenever you use water from the cultured jar, refill it with some aquarium water again to continue the culture.

If you need infusoria urgently, add some milk yeast to matured aquarium water in a jar and leave it for 24 hours.

Use it to feed the fry(s) similarly. There is no need to wait for the food to decompose in this method.

Brine Shrimps

Brine shrimps are highly nutritional and initiate a predator instinct in baby fish. This instinct is essential for their survival and growth. Hence, they make one of the best fish fryfoods.

You can hatch a few brine shrimp eggs in 24 to 48 hours using a hatchery and dry shrimp eggs.

Both of these are available in stores (online/offline).

Keep the unused eggs in the same packet in cold storage for the future. Hatch them as and when needed.

Use all the hatched eggs on the same day. You cannot preserve them for later use.

Readymade baby brine shrimps are also available in stores.

Green Water

Water with a lot of algae in it turns greenish. Hence, the name.

Green water is a preferred baby fish diet of herbivorous fishes. Many omnivorous fish fry(s) also accept this food.

 Add some algae scraps or grass from the main tank in a large jar filled with matured aquarium water to culture green water.

Leave it for a week in a sunny place.

Keep stirring it daily as it turns greenish. When the entire water becomes opaque green, you can add some green water to the fry tank.

Whenever you use green water, refill it with some aquarium water to continue culturing.

Egg Yolk

It is the handiest food while managing unplanned reproduction in fish tanks or if you are not ready with cultured fry foods.

Even otherwise, it is easy to make.

Boil an egg and separate the yolk. Add some water and stir it rigorously till there are no yolk lumps left.

 Tie this thick yolk mix in a fine cloth such that you can squeeze a little egg yolk into the tank.

Do not drop extra yolk while feeding. It will be messy to clean it.

Veggies and Adult Fish Foods

Remember, livebornfish fry(s) can eat the same food as adult fish (in smaller portions) from their birth.

You can feed veggies like Zucchini, Boiled Peas, Broccoli, Boiled Carrot Slices, etc., in small portions, to all fish fry(s) as they grow.

They will eat adult fish food gradually.

Adult fish foods include:

  • Dry foods – like Flakes, Pellets, Wafers, etc.
  • Live foods – like Bloodworms. Cyclops, Plankton, Krills, Brine Shrimps, etc.
  • Frozen food – Live foods in a frozen state.

Adult fish also love to eat the veggies listed above.

Transfer to a Grow-Out Tank

As the fish fry(s) grow in size, the fry tank is insufficient to house them.

The fry(s) are growing but are not large enough to be added to the main tank.

Hence, prepare a grow-out tank while hatching the eggs and feeding the newborn fry(s).

It will be ready to house them when they grow.

Maintain optimal tank water parameters consistently and feed them with varied diets for a balanced diet and proper growth.

When the fry(s) grow large enough for the adult fishes to eat them, move them into the main tank.

Colony Breeding

If you do not have a grow-out tank, try this method.

In colony breeding, the yet-growing fish fry(s) are kept in the same tank as the adult fish, although it is unsafe.

Densely thick plants, large wads of Java moss, rocks, a hanging mesh of plant roots, etc., are added to the main tank.

These provide small spaces for the growing fry(s) to slip in, reside, or hide, keeping them safe till they are ready to venture into the main tank.

Avoid colony breeding as:

  • You may lose some fry(s) to adult fishes.
  • The main tank should be large enough to add the new fry(s) with additional hiding spaces etc., without overcrowding.
  • It might compromise the quality of tank management due to increased bio-load and little open space to clean the tank thoroughly.


Hopefully, this article has empowered you to take care of fish babies.

A gentle reminder – ensure everything that goes into the different fish tanks (including food) is good quality and bacteria/parasite free.

Fish eggs and fry(s) are as fragile as human babies.

Unfortunately, there are no proactive vaccinations or medications suggested for them.

The main focus is on protecting and feeding them to become healthy adults.

When your patience and hard work pay off, you will swell with pride, watching them swim in the community tank.

In turn, they will thank you for their lives.

Well-bred fish can also be commercially rewarding if you plan to sell them.

We wish you a happy fish grandparenting time!

About the Author

Shelby Crosby

Shelby is a passionate fishkeeper who has been writing about fish for over 5 years. She is a pro aquarist and holds a BSc Honors Degree in Wildlife and Fisheries. She creates her own beautiful aquarium layouts and loves to share her knowledge of tropical fish with other hobbyists.

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:

  • BSc Honors in Wildlife and Fisheries in 2011 (University of Northern British Columbia)
  • Completed her undergraduate thesis on the effects of zoochlorella supplementation on the growth and health of fish.

Writing Experience

Miss Crosby is a Freelance blogger; many of her articles are posted online on various blogs. She has also written a few short articles for "Tropical Fish Hobbyist Magazine" in the past. She is a regular contributor to Her education, first-hand experience with fishkeeping, and in-depth knowledge in aquaculture make her one of the most competent writers in the industry.

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