A baby? They always look like girls with fake eggspots and short fins.. Let her grow out for a month or so to let her fins grow. If it's actually a male, then that's going to be trouble. :o Remember the tank has to be cycled, heated, and heavily decorated or planted. Females are just as aggressive as males. :)
Their tail type won't matter much. So you can mix them together. Put in the least aggressive 1st and then the most aggressive. That way the aggressive ones don't feel like their territory is being invaded.
Their age won't really matter as well, just their size. If big girls are with small girls then they're going to be beaten up easily basically. I'm getting a sorority soon too so good luck! (;
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