My common oscars...

Question
I have three oscars, maybe 2-2.5" in a 10g tank. 1 white, 1 black, 1 orange. I've been watching them to pick up on their behavior. I bought the black and the orange oscar at the same time from the same tank, the white one came a couple days later. They seems to get along fine when I am observing. In the begining the black one was the domonate one, agressive when it came to feeding. The orange would always hide in the castle.(Not to mention the strange behavior it had the first day or so after being placed in a new environment). When the white one was placed in the tank it was almost harmony, until rolls shifted. Now the white oscar and the orange oscar paired. Well the black oscars behavior changed drasticly and its feeding habits decreased. I am currently feeding them feeder fish, worm and shrimp brine cubes and occasional sweet peas. Last night I was observing them after putting feeders in the tank, the other two eats quite well. The black one wasn't game to eat I hadn't feed since the day before. It gasps and its gills open up so far and its something I haven't seen either of them act this way. I love all three of them and im trying to keep the healthy until I can finish my 55g aquarium. Why is the black ocar bahaving in such manner? I was think buying another for companionship. What do you suggest?

Answer
Hi Antoine,
You have quite a crowd in your 10 gallon aquarium. Keeping the water quality stable and healthy will be quite a task even with baby oscars. The black oscar may be gasping due to water pollution problems. Toxins produced by the fish like ammonia can make breathing really hard for fish as well as prolonged high nitrates can trigger illnesses.

In a tank like this (until you can get your 55 gallon setup fully) I would do about 75% water changes on this tank everyday. Make sure to use a good water conditioner when adding replacement water back like Amquel+ or Prime and make sure the temp is equal to or just a bit warmer than your tank's temp.

With all the feeding and stuff that oscars require and the waste they naturally produce anyway, it is critical that you keep their water very clean to avoid the danger of setting them up for life-long health problems that are difficult to cure like "hole-in-the-head". Just keep up with big daily water changes.

You should visit here for some of the best oscar info around-

http://www.oscarfishlover.com/

I hope all goes well and best of luck!
Karen~