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One of the great joys of fishkeeping is when your fish make new fish! Catching a glimpse of a tiny pair of eyes and a tail swimming in the aquarium for the first time is fascinating. This article aims to look at the various methods of fish reproduction and how to care for young fish in your aquarium.


Where do baby fish come from?

With over thirty thousand different species of fish found across the world, it comes as no surprise that they have evolved a few different ways to reproduce. The overwhelming majority of species are egg-laying (oviparous), but quite a few give birth to live offspring (viviparous).  The majority of fish spawning results in the fertilised eggs being left to take the chance against nature, where only the lucky survive.  But there are a few families of fish who have evolved parental skills to increase their offsprings chances of survival. As a a general rule, those fish who offer no protection will counter their lack of quality with their quantity. These species release many more eggs than will ever develop and survive. Fish who exhibit parental behaviour will lay fewer eggs, but increase the survival rate by protecting them until they can fend for themselves.


Cichlids are a great example of good parents - with nearly every species providing protection to their young for a period of time. Some build and defend a nest, others take their young with them. The fascinating cichlid Tahuantinsuyoa macantzatza from South America lays their eggs on a leaf or small stone. They either find a safe spot to leave it, or take it everywhere they go to protect their eggs. Many species of Malawi cichlids are mouthbrooders. With this method, after fertilisation, the female takes the eggs into her mouth. During this time she will not eat, opting to starve for the sake of her offspring's safety. Once the fry are brave enough, they can leave the comfort of their mothers protection, but still return if they sense danger. It's an awesome sight, witnessing lots of tiny eyes peering out of their mother's mouth, deciding if they are ready to venture in to the world!


Other families of fish that offer protection to their young include arowana (mouth brooding by the male), gourami (males defend a bubble nest), Loricariid catfish (males defend the eggs) and even piranha (both parents build and guard a nest)!


For many fishkeepers, the first experience of baby fish comes from livebearers (guppies, mollies, platies and swordtails). Unlike mammals, where the young are nourished by the mother, livebearers eggs are stored in a protective chamber and develop from their own yolk. This chamberbecomes visible during pregnancy and is the gravid spot. When the young are born, they are more developed than egg-laying fish fry, so are able to swim straight away. This is essential, as these live bearing fish do not offer any protection to their young! Its swim and hide, or be eaten by your own parents! Planted tanks offer good protection for these tiny fish, giving them time to grow until they are big enough to not be considered food. Hobbyist intervention is the key to increasing survival rates amongst species who have no parental care.


Caring for baby fish

The level of care young fish need depends on whether they have help from their parents. For non-parental species, separating the young as quickly as possible increases the rate of survival. The gravid spot on pregnant female livebearers is a good indication of their stage of pregnancy. When this darkens, it is time to separate them into a maternity ward. These separation units are usually made from net mesh or plastic and sit inside the aquarium. They will have a divider with small slots or holes that separates the top and bottom half of the device. The female fish is moved in to the top half. When she gives birth, the young will fall through the divider into the bottom half, out of harms way.


Having the mother and fry in the same water as the aquarium is important. This significantly reduces stress of moving the fish and retains the same water parameters. Fish should only be moved into a separate aquarium if the filter has been cycled in a mature tank first to prevent water quality issues.


For fry who have dedicated and caring parents, they can be left in their care for a period of time. Many fish species will give their young a defined period of time before being made to fend for themselves. This length of time varies, but generally it coincides when the parents are ready to breed again. Its important to remove the young before this happens if you wish to rear them. It is hard to determine that length of time, but a good general rule of thumb is to remove the young once they are searching for food independently. A good method to remove the fry without disturbing the aquarium too much is to siphon the young out in to a bucket, strained through a fine net. The parents will likely be aggressive to the tube but it is an effective way to remove small fry. These fish can then be transferred to a breeding unit similar to those used with livebearers. Because there is no adult fish in there, the divider can be removed to maximise the space for the young fish. Not all fish parents want to get rid of their kids though. The fairy cichlid Neolamprologus brichardi from Lake Tanganyika create nuclear families. Their offspring are welcomed to stay and help guard the younger generations of their siblings.


Feeding baby fish

Young fish are too small to take regular fish foods - it doesnt fit in their mouths! The dietary needs of fry also differs from adult fish. For these reasons, it is recommended to have specially formulated fry foods for young fish. NT Labs Pro-f Micro Crumb is the smallest granulated food (0.2mm or 200µm) in the Pro-f range and has been specifically formulated for small and young fish. It is a quarter of the size of the next closest granule: Pro-f Nano Tropical! Micro Crumb has a higher protein content than Pro-f Tropical to provide the high energy requirements needed during early development. Micro Crumb also contains Stimmune”, an ingredient derived from yeast products that encourages strong immune systems to fight off disease.


When feeding such small foods, it is important to target feed. First mix the required amount of fry food into a small amount of water. Using a syringe or pipette, direct the food suspension to the area near where the fry are in the aquarium. Feed little and often is the best approach with fry, due to their high metabolism. This also helps prevent food waste which can foul the water and encourage bad bacteria and fungus to develop in the hatchery.


An alternative to micro foods is live foods. Many fish breeders use newly hatched brine shrimp (Artemia nauplii) for feeding baby fish. There are many benefits to using this live food, although it also comes with its fair share of preparation and production. Unless the fish require live foods to hunt, most fish fry (both from egg laying species and live bearers) will take to fry foods straight away.


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