Zebra Danio Breeding, Fry Rearing, and Improving Bloodlines

Zebra danios are probably the easiest egg-laying fish to breed. They are sturdy little fish that can breed in a wide range of water conditions. The main difficulty is not to make them lay eggs but to keep them from eating them.

That’s right, danios are voracious egg-eaters. Putting them in a bare bottom breeding tank, without any separation from the eggs guarantees a feast you won’t enjoy that much.

But first things first.

Breeding Danios: Tank Setup, Sexing, and Conditioning the Fish

Danios are very easy to breed. You may end up with fry even if you do nothing else but feed them protein-rich food. Here’s how you can take good care of them.

But for better breeding results, follow these steps:

1. Sex the danios. Females have slightly paler colors and considerably plumper bodies than males. Two males for every female tend to produce the best results. Danios reach sexual maturity around the third month of their lives.
2. Condition the danios for breeding by feeding them live (or frozen) high-protein food like bloodworms. A week usually is enough to see the females growing considerably rounder bellies full of eggs.
3. Move the danios to a breeding tank. This can be anything from a small glass aquarium to a plastic or styrofoam box. Danios will breed in shallow waters so 6-10cm or 3-5 inches will suffice. Danios are jumpers so cover the tank. The water must be cycled. Adding a breeding mop (tying together 25-35 strings of acrylic yarn will do the trick) or java moss helps.
4. The light should be medium to low. Danios will spawn early morning.
5. The most important thing is to create separation between danios and eggs. You can do this by using a plastic mesh or by covering the bottom of the breeding tank with pebbles. Using a mesh, breeder net, or a plastic basket with small holes is more effective because danios will try to eat as many eggs as they can find and they will scour the bottom for eggs.
6. Water conditions are fairly broad, as danios can spawn even in cold water. Still, provide pH of around 7.5 and a temperature of around 22-26°C or 72-80°F.

That’s the overview. The same principles apply to all kinds of danios — leopard, spotted, giant, Glofish, and so forth. While their markings and colors differ, all danio species reproduce the same.

Now, let’s break it down in greater detail.

How to Raise Baby Danios

Baby danios hatch 24-48 hours after the eggs have been laid. They are absolutely minuscule at first and must be kept separated from their parents. Otherwise, the big fish will devour them with much gusto.

Bare bottom tanks are generally better for raising danio fry. Maintaining stable water conditions in a bare bottom tank is much simpler than in a tank with substrate, even if the substrate is inert.

What’s more, the lack of substrate allows you to see any dirt buildup. You can add a clump of java moss or hornwort to the breeding tank. The plants add filtration, hiding space, and infusoria for the babies to munch upon.

Feeding Baby Danios

Newly-hatched danios are mostly eyes — about a third of their body mass is eyes. Their mouths are tiny and so are their bellies.

Here’s how to feed them:

1. The first couple of days after hatching, the fry won’t swim around. There is no need to feed them because their spawning sacks will provide sustenance.
2. Feed the fry 2-3 times a day once they start swimming. Their stomachs are very small and can’t hold much food.
3. Give them pulverized flakes, infusoria, or egg yolk. Hard-boil the latter, diffuse it completely in water, and administer it with a syringe or pipette.
4. When feeding, make sure to spread food across the aquarium so all babies have access to it. Remember, they are tiny and can’t swim that much.
5. Adding a few snails or cherry shrimp will help keep the fry tank clean, as they’ll mop up any uneaten food.
6. After about a week, the baby danios can eat brine shrimp. Brine shrimp will make them grow faster.
7. When the danio fry is big enough to consume brine shrimp, move them into a grower tank.
8. The grower tank setup doesn’t need much water — 10-12 centimeters or 5-6 inches of water is enough. Add java moss or hornwort generously. A surface-floating plant like duckweed also helps in keeping the water clean and in providing security for the baby danios.
9. A sponge filter or two is everything that you need in terms of filtration. Cleaning crew like snails, shrimp, or even plecos also helps.
10. Continue feeding the small danio fish 2-3 times a day. The cleaning crew will take care of food excess so spread it around generously for the fish to feast and grow.

Improving Your Danio Stock

Improving fish genetics is a massive topic in itself, but there are a few basic principles to follow.

For starters, select the best-looking fish for consecutive rounds of breeding.

To avoid undesired genetic mutations, diversify the stock. Inbreeding increases the odds of deformed, sickly fish manifold. Buy high-quality fish from the local fish store to diversify the bloodlines. It is best to select the fish yourself instead of purchasing them online if you really want to improve your baby fry.

When choosing new fish for your danio breeding project, look for healthy individuals, with bright colors and normal behavior.

It is entirely possible to create your own subspecies by mixing, say, zebra danios with leopard danios.

Enjoy the Danio Swarm!

Danios of all kinds are prolific breeders. A single couple can lay over 300 eggs at a time! If all the eggs hatch, you will end up with a ton of fry.

And in three months they will be sexually mature to start reproducing themselves.

Enjoy the danio madness!