Infusoria can be used to feed egg laying fish fry. This tiny freshwater equivalent of plankton can be used for all sorts of fish fry. The good thing is you can time it so that by the time they’ve used their egg sac up they can be eating the flourishing tiny little infusoria. Even an impromptu batch of eggs can be fed with these tiny little organisms.
Fish eggs will most likely get eaten quickly. It’s best to remove them and put them in a tank of their own. If they’ve already hatched you’re still in luck. Move them into a tank of their own as soon as you can to avoid them from being eaten by the parents or tankmates.
Newly Hatched Fry Live Off of Their Egg Sac Briefly
Generally, it takes a couple of days for the fry to consume and exhaust their yolk sac. If they still have a yolk by the time you discovered them there is a good chance that infusoria can help grow these tiny fry. If there is no yolk, you may not have time to start a culture before they need food.
Many commercial foods are too large for small egg layer fry. There are some commercially available fry foods, and boiled egg yolk can work also, but often they are too big. Your best bet is with infusoria. Old school books talked about infusoria quite a bit when discussing rearing fry. Somewhere along the way, it got pushed back into the far reaches of the hobby.
Infusoria Are in Streams and Ponds Naturally
Infusoria are small little organisms that live in freshwaters like ponds, rivers, and streams. They are also found in aquariums but it’s likely you won’t be able to see them. There’s also probably not a lot of them in there.
Infusoria is a catch-all term for algae, euglena, paramecia, and other protozoans. Rotifers and non-photosynthetic paramecia are the most nutritious for your new fry. Luckily they’re all easy to grow. Algae and rotifer alike.
Infusoria may grow in rivers, lakes, streams, and ponds but you don’t want to get yours from there. All sorts of nasty little critters live in that water as well and you don’t want to introduce parasites and predators into your fry tank.
You can use tap water if you let it sit and age or you can use water from your aquarium when you do a water change. If you have a planted tank it is more likely to have more microorganisms in it which is beneficial. Some like to squeeze out a sponge filter into the water when starting a new infusoria culture. Other like to vacuum snail feces up as they are high in plant matter.
In addition to aged water or aquarium water, you are going to need some organic matter to feed the culture of infusoria. Some of those old books say to use hay or old grass by first boiling it, and others suggest using an old leaf of lettuce in the water. Brewer’s yeast tablets and cucumber or zucchini skin can also work. Rabbit food pellets which are usually made out of Timothy hay can also work by placing one pellet per container.