Hi everyone! I received my 3 Aphyosemium Striatum Killifish today (1 male and 2 females). I have never seen these fish in person, so I honestly wasn't too sure what to expect (in terms of size). They are pretty small, so I think they must be juveniles? They are about 1 inch long. I have 5 fully grown Diamond Tetras and 3 Pearl Gourami in my tank. The largest Tetra is about 2 inches long (his body is much wider than the killifish though), so he's much larger than the little killes. Two of the Pearls are about 2 inches long and one is 3 inches long. I'm worried about releasing the killies into my tank, because they are so small. Last weekend, I tried placing 3 new cory cats in the tank. They were very tiny (about 1/2 inch long), and I'm new to fish keeping, but I figured since the lfs was selling them, it must be ok. Also, the cories were kept in a tank with tetras and pearl gouramis at the fish store, so I thought everything would be fine. Well, when I placed the cories in my tank, the Diamond Tetras immediately bit off the tail of the smallest cory and part of the tail of one of the other cories, and even though I medicated the tank & placed the cories in a baby fish keeper, the smallest cory died. Now, I have the killifish in a baby fish keeper. Do you think the killifish will be able to hold their own against the Tetras? (The Pearl Gouramis don't seem to bother anyone else) If not, will they be ok in the baby fish keeper for now, or should I go purchase another fish tank?

Thanks again!

Ideally you should have another tank set up as a quarentine tank - this way you can keep an eye on them for a few days and make sure they aren't sick/diseased. If they are and you put them in with you tank, you will infect the whole tank. It doesn't sound like you have anything ready to keep fish in so you will just have to take your chances I think. It isn't fair to keep fish in a fry net.
Most species of killifish stay fairly small, so they may be as big as they are going to get.
Im really not sure how the tetras will react. When you do release them, keep a close eye on things and be prepared to take the killis out and place them elsewhere.

Thanks, Breeze 7050. I actually had to go ahead and release the largest female into the tank b/c she was being aggressive towards the male killifish-I thought this was curious (isn't it usually the other way around?) She nipped his tail fin. So, she is now swimming in the tank. The tetras and Pearl Gouramis have approached her (the Gouramis flicked her with their feelers and the tetras just swam up to her). They seem to be acting ok, but it's only been about 30 min, so I'm watching very closely. If all goes well, I'm going to release the remaining two killifish into the tank in the next few hours or so. Thanks for your advice-it sounds like we should purchase that 2nd tank.

Just a little update...I released the remaining two Killifish into my tank yesterday evening. So far, everything is going well. The tetras have examined them, but that's it. No nips or prolonged chasing. The Killis ate today. They do seem to spend quite a bit of time near the bottom of the tank (in the most heavily planted section of the tank). I thought they really prefered the top of the tank? So, maybe they are a bit wary of the tetras. The male doesn't act all that scared of the tetras really. He swims out in the open swimming area (where the tetras spend most of their time) and allows the tetras to have a good look at him. He must know he's a dreamy fish. Then, he just meanders around until one of the tetras darts at him. He swims into the plant, and then he's back out a second later. I've only seen the tetras take one or two darts at him. But, I've also seen him dart back once. The females seem to be much more cautious. But, overall, I think everything may be ok.

Sounds like everything is going good. keep us updated!