Mixing the Meanies

"I want a tank full of really mean fish that all get along." .

I had a young customer make that statement the other day, completely oblivious to how contradictory it sounded. Think about it; fish either a mean OR they get along, but both?

Many hobbyists do manage to mix some rather nasty critters (cichlids, pacus, big catfish) indefinitely, but others wind up with a solitary super-aggressive fish with a big grin on his face. Oddly enough, two aquarists can have such opposite results even if they tried exactly the same mix of fish! In fact, it is nearly impossible to answer the question, "Can this fish mix with mine?" when dealing with an aggressive community. It's not as simple as just knowing that "Oscars get along with Jack Dempseys" or "African Cichlids mix with Firemouths". Sometimes it works and sometimes not.

Here are a few thoughts on how to keep the tough guys together:

1. Start with young fish. Get everybody used to each other's presence before they mature and become more territorial.
2. Pick fish that are similarly aggressive.
3. Start with the least aggressive species, and work your way up to the more aggressive.
4. Less aggressive fish should be somewhat bigger than more aggressive ones.
5. Re-arrange decorations moments before adding new fish to break up established territories.
6. Watch new additions closely for a few days. A fish that is continually harassed will not last long.
7. Get a big enough tank. Fish that might get along well in 100 gallons might be at war in a 40 gallon.

Submitted by: Jim Kostich

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