long term in the home aquaria? nothing. short term...other gars of similar or larger size. they will generally eventually outgrow 95% of the usual predatory tankmates and attack, maim, eat, or kill them in most cases. gators are not ideal tankmate fish--
--solomon
3 gars, 3 paimas 2 RTCs - so far so good. Most of the tank mate killing is conducted by RTC.
Gar and RTC have one silver aro under their belt each. RTC also have an O and a paima to add to tally. But now that paimas are growing fast, gar are no match for them during feeding (except for oversized things - paimas are wimps when it comes to large food - got a horror story of LFS paima chocking to death on snakehead - sheesh).
PS: not sure who killed the three red bellied pacus ... still got two left in the sump ...don't know what to do with them ... test the water in the new aquarium?