Ballon mollies with big goldfish and Iridescent Shark Catfish

Question
Sorry to bother you..I really worried about my new balloon Mollies with big fishes around and they are getting ready to release eggs. Do I have to use the breeder tank with or without the air pump? Is it ok to put balloon Mollies with other large fishes? Can I use sponge to keep the fry or egg in there for a temporary safe place?(I am lazy to buy breeder box) Thanks:)

Answer
Hi Toby,

Mollies CANNOT be kept with Goldfish. Goldfish are cold-water fish, which means they need temperatures of 70F or below. Mollies are tropical fish, and they are one of the higher-range tropicals requiring a temperature of at least 78F, preferably 80F, for best health. The iridescent shark would be OK with the Mollies, but it would eat any Molly fry.

You can place the pregnant female Molly into the breeding tank to separate it from the other fish, so that they cannot eat the fry. Provide some floating plants at the top, because Molly fry naturally have the instinct to swim to the top and hide. Using an air pump would be great, since the female Molly likes good oxygenation during birth, as this takes a lot of energy!

When you say "Is" it OK to put Balloon Mollies with large fish?", how large are they? It's actually not a matter of size, but rather, a matter of species. Things like large Plecos and Bala Sharks would be fine, but smaller things like Tiger Barbs may actually not be a good choice! As long as the large fish are classified as 'peaceful community', it should be fine with the Mollies. You should introduce the large fish last, to reduce any possible aggression.

Mollies are Livebearers, which means they give birth to live babies, instead of laying eggs like most fish. You can remove the female after she gives birth. Keep in mind that the whole birthing process can take a whole day (from first baby to last baby!)

You can use a separate breeding tank or box to house the fry in until they are larger not to get eaten. A sponge filter would be perfect.

Good Luck, and Happy Fishkeeping!