Although not new to keeping fish, I am new to the world of Cichlids. "Don't get Convicts" so I was told, "unless you want to be over run with them!" I got 2 and within 2 weeks I noticed the male got extremely dark in color and the female developed the orange spots on her sides along with beautiful purple and blue coloring on the fins! Prior to this the 280 L tank was peaceful with 4 Rainbows, 1 Kribensis, 2 Angel Fish and 1 Geophagus with the occasional territorial spat between the Geo and the Convicts with the Geo being top fish. Then the babies arrived and the Convicts showed their true colors! NO fish gets anywhere near these babies! The babies are herded all over the tank and guarded without mercy towards all fish. One week after the first batch of fry, MORE eggs, more fry! So ends my adding any "new" fish to this tank as I'm sure it would be viewed as an intruder by the Convicts. Am I sorry I got them? NO! They are the "most" interesting fish in the tank and observing this parental behavior is extremely fascinating. It does seem though that the Convicts are not bothered by any of the fish except the Geophagus, who by the way, has "learned" to stay away from them. The only problem is no one can possibly keep the amount of fry these fish produce.
I have a pair of Convicts that live in a tank with a Green Terror and a Blue variety of African Chiclid. Although the convicts are aggressive, they never challenge the Green Terror even though he is very peaceful and not much bigger than them. The Blue African loves to pick a fight and if not for the fact that there are 2 convicts, he would rule the tank even though he is half their size and about a third of the Green Terror. I find that if you introduce the convicts after other cichlids have settled in the tank, they are not that aggressive. A beautiful addition to any tank.
I have one black convict in a 140 L tank with a variety of other fish including lemon tetras, chromides, chocolate cichlids, red finned shark, spotted puffers, green scat, severums, and even a swordtail. I have had no problems with my convict being aggressive. As a matter of fact the convict is scared more by the shark than any fish of it.
I introduced a pair of convicts into a tank which already had a slightly larger oscar in it. The pair of convicts never seemed to get along. One morning I found the female lying dead on the bottom of the tank with a couple of terrible wounds. I don't know what went wrong - I suspect that the female was not healthy and the male instinctively killed her. Since her demise the male has turned his attention to the oscar, which now stays in the farthest corner of the tank. I have two pots in the tank which he has claimed as his territory. He is so arrogant that he even attacks my finger when I try to rearrange the pots. (An attempt to break up his territory and make him less aggressive). I was pretty mad that he caused havoc in my tank - but it's quite something to see the way he dominates the tank. He's got a lot of character.
Update on the Convicts! After about 2 weeks of the parents herding the fry around the tank, there territory became increasingly larger which meant the other fish in the tank were literally banned to a tiny corner. I made the decision to move the parents to another tank but the babies just could not be caught. I have spotted several babies surviving and GROWING though. They are survivors that's for sure! They hide under pots, rocks and driftwood. They now "look" like little tiny Convicts but are still too small to venture into the main part of the tank. By the way, the parents, although upset at first after their move, have once again laid eggs within a week of being moved, and the fry hatched out today (5/7). I was shocked to see how tiny they are compared to the first time I noticed the babies from the original batch, which leads me to believe the first batch were probably 2 weeks old before I ever noticed them! To comment on the aggressiveness, these fish definitely will protect their young even against a human hand! Trust me, I've been nipped!
I started with two small Convicts (3-4 cm) in a 40 liter tank with a pair of True Red Zebras (5 cm) and the male Convict was lucky to survive. I had to borrow two more (5-8 cm) from a friend as reinforcements for him. It did not help much, the Zebras still hunt him. If the Convicts stay in a group they can keep the Zebras at bay and the Zebras never mess with the biggest (8 cm) Convict. The Convicts may be bad fish but at least this time they have more than met their match with these Zebras.