i can't believe that the jd ATE the oscar.....:'(

if the oscar is bigger than the jd it could be over territory or just trying to be the dominant fish

yup that's cichlids for you. what size tank are they in, which one was in it first and when was the second one added ?

there's a reason they're called jack dempseys; very pugnacious fish...plus as with any cichlid you can always end up with one which is a bit of a characer (i.e. a murderous thug).

probably he didn't see the mollies as being in any way a threat to his territory/breeding rights, as opposed to the Oscar which clearly would be perceived as such a threat.

One thing to try when adding cichlids to cichlid tanks (always a bit hit and hope) is to substantially re-arrange decor so that the original inhabitants are thrown off balance - it confuses them a bit ('hey this is all new') and they will be focusing on establishing new territory rather than defending old. Equally this will make them less inclined to fight hard with new inhabitants in the initial stages. What you're then hoping for is that everything settles down in some sort of equilibrium.

JD's are vicious little fellas. Just like RD's. The Oscar and the JD's just behave differently. I wouldn't mix the two personally. As Coler asked, what size tank are they in? Tank size would play a great deal of importance in these types of territorial fish.

you can mix these species..the issue is tank size and cover. you need to make sure there is plenty of hiding places in the event that cichlids act like cichlids.
I've seen plenty of set ups that included large JD with large oscars..but they were in large(200+ G tanks)

well at least the oscar did not eat him lol. the oscar will recover. move your tank around and get it looking all new and i suspect that you will be fine. the reason he did not attack the mollies is because as stated before they are not a threat and another cichlid in the tank is. you had a lot of mollies in the other tank right? who is to say he didnt get snacks between feeding.

no reason to be surprised. . . . you've been asking about your stocklists constantly and whenever you've been told a tank is too small or the fish won't get along, you say you'll bring them to the store but you never do. this is why you should actually take advice once you ask for it.

i can't believe that the jd ATE the oscar.....:'(

Well,,believe it, u've been told several times in another thread, it was a gamble and u lost. But now u know.

hmmm...its perhaps not that unbelievable...they would appear to be in a 29 ? http://www.aquariacentral.com/forums/showthread.php?p=1164698#post1164698

its too small a tank to keep those fish in...cichlids you could consider in there would be apistogramma, rams, tanganyikan shell dwellers, a convict or two (I think), some small central americans (thomasi)...maybe 2 jewel cichlids.

As long as they are in that tank one will beat the head off the other.