My jack dempsey sits on the bottom of the tank

I have 1 jack dempsey, an albino and a black oscar. The 2 oscars are always swimming around but the jack just sits on the bottom on the tank. Im kinda worried, is that normal? He hardly ever moves, but I've had him for about 6 months now and he seams and looks healthy. I usually throw about 20 feeder fish in my tank and the oscars tear them up the second they hit the water but the jack just sits on the bottom and hides behind his little rock. I barely ever see him eat. We feed them pellets everyday and I never see him come up to the top to eat but the oscars are always up there once I put them in. They even jump out of the water and bite my finger! Ha ha its pretty funny, their vicious! But the jack isnt & I did allot of research that said jack are the most agressive out of the cichlid family but hes the least aggressive in my tank. The albino and him fight a lot but the jack backs down & goes right back to his little rock. Its funny too, because the black oscar and the jack sometimes both sit behind the rock and the oscar will either sit on top of him or next to him. Its kinda cute!but he never eats! He just sits on the bottom! Hardly ever moves around! What should I do? Should the water be a certain way? Maybe the water in the tank is too cold for him because I dont have a tank heater? Should I check the ph levels? Help me somone, I dont know what to do! Its starting to make me mad because I never even see him, hes always hiding! Helpp mee. Thanks [= xo

You should definitely check the PH levels. Cichlids like a little salt too.

Also what kind of decor do you have? Jack Dempseys and Oscars aren't keen on bright lights, so make sure there's some vegetation (real or fake) to dullen up the lights for them.

I'm also very concerned that you feed them 20 feeders at a time. That's way too many. You should only do one fish per predator until those fish are gone, then maybe add a couple more. Jacks and Oscars can cause a big mess when feeding on live fish, so be sure to clean the tank more regularly. (also pay close attention to any spots on your fish, often times feeders carry diseases that can infect your cichlids)

Cichlids also like a variety of foods, try getting some krill to feed them too.

I also want to warn you, jack dempseys and tiger oscar will get big very quickly, especially when fed live fish. You may need to purchase a bigger tank very soon.

xox
Sika