i heard that new females are usually pregnant from random males in the pet store so you shouldn't keep the first litter if you want your male's offspring. i also heard she can keep random males sperm for multiple litters. if this is true, roughly how long will it take to know i have my male's offspring? also i heard that you don't want to keep either runts or especially large fry. why not larger fry ? and what breeds have the most color variation in offspring?

as a rule of thumb, females are generally found to be pregnant when you buy them, though this is not always true. and yes, females can hold sperm and have multiple batches of fries by only having only bred once. as for you other question, i can understand not wanting the runts but ive never heard anyone tell me not to keep the larger fries. the truth about this concept of "runts" and "larger fries" is that most people raise their fries (generally 30 +) in a 10 gal give or take. this causes overcrowding and some fries receive more food than others , therefore growing larger. the smaller ones tend to recieve the fewer food and stay smaller. if you were to raise a whole batch of 30 + fries in a 55 gal i can almost guarantee you wont have to runt/larger fry problem (still depends on if they can find enough food in such a large tank). if you did decide to raise only the fries in a 55 though, i would (and so do most people i know) consider it a waste of a tank, hence most peole end up with the runts/larger problem. as for the sexing, that all really depends on how good you are as an aquarist. i usually have to wait until their a little larger than 1/2 an inch before i could tell

i always kept the spawns after 3 spawns. It takes that long to clear the sperm bank. I always keep the ones that are the color I want and the most robust.

60 years of breeding and raising tropical freshwater fish