Super Aggressive tank

[irisheyesinme]

Hi, I am relatively new at this fish thing (about 2 years - but I have figured out breeding!). My fish are mean, I mean really mean. I have one fish (I rotate them in and out as they heal and then another gets beaten) in quarantine at almost all times, sometimes more, as the others have beaten the tar out of it. I have tried lowering the tank temp.(can't seem to get it below 82/84 even with the heater set to 76/74) and have tried to crowd them. Today I went and got 2 more and by the time I got back from the park with the kids one one cowering behind a rock with a wrecked tail and the other has been hiding at the top behind my qurantine box (that I put the wrecked tail fish in). I have a 55 gallon with 2 filtration systems. I do a 25% water chnge weekly, sometimes more every few weeks or so. I have tons of hiding spots. I love this tank thing, but am getting fed up with the aggressiveness. I do also try to mess up the tank, territorily speaking, when I introduce new fish. I have about 17 fish in this tank. Please please pleasse - any suggestions????? Thanks!

[irisheyesinme]

anyone?? anyone?????

[cichlidfish]

i think your post got lost in the moderation queue...by the way you forgot to mention what kind of fish you have in your tank!
And also how big they are! I wonder if they are red devils or similar?