Arowana and peacock bass
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Side note for poster above, less then 5% of tank kept Arowana's reach 48 inches. Better estimate on adult size for tank kept Arowana's would be 36-40 inches. Out in the wild then yes 48.
JV
Forgot my source sorry. Normally I think wiki is worthless but found this to be interesting. Please see in aquarium highlighted section. "As aquarium fish they are voracious and predatory, eating any smaller tank mates and fighting with others of equivalent size." Fighting with equivalent size.that should tell you right there, very big potential problem. You're just rolling the dice. I'm sure it's worked out for SOME, but enough to say go for it? Sorry not from me, I like my Arowana alive.
It depends on which one is bigger. Both fish are predators that will eat anything smaller than it is. Arowanas get enormous, too, so think ahead -- even with a 250 tank, what do you intend to do with the arowana when it gets to be 4 feet long?
Depending on the relative sizes it should be an OK combination,at least until the Peacock reaches sexual maturity and stakes out a territory. It would also depend somewhat on which species of Cichla you could get. There are 3 or 4 different species.
The worst that could happen would be that you wind up with a bunch of Arrowana scales and a Peacock that needs a larger tank(it could happen,the world record for hook and line for a Peacock is 28#.)
i have owned both silvers and peacock bass.