I have just succesfully bred my fist pair of Jaguar Cichlids and am impressed with the amount of fry that they produce (see photo). Water conditions must have been pretty close to perfect, also mine have the advantage of having a 250 liter tank with no other occupants. The male is now showing really aggressive behaviour, but the display of parenting is second to none. I would recommend anyone who is trying to breed Cichlids to try with these, as it is an experience to see so many young gaurded like they are royalty.
Nandopsis (Parapetenia) managuensis is one of the largest species in the cichlasoma genus, reaching 35 to 50 cm in standard length. Jaguar guapotes are hyper-aggressive predators that will accept any meaty items, such as chopped fish meat, earthworms, krill, crayfish, and bloodworms. These are rated as one of the most aggressive cichlids available in the trade. Their pugnacity is similarly compared to the closely-related Parapetenia doviis or umbriferas.
I have two Jaguars in my 350 liter tank. One is a 34 cm male that I rescued from the local pet store at around 20 cm. He was in a 40 liter tank and could barely turn around. He has become my favorite fish over the last 5 months. I have always kept Oscars because I like the personality that they show, but this Jaguar rivals them in that regard. I also purchased a small 4 cm Jaguar that is now about 15 cm. Both are very efficient eaters, taking pellets, flake, live, frozen, etc. The large male is a digger. His desire is to move all of the gravel in the tank into a large pile in the center. I smooth it out every week when I change the water and vacuum the grave, but it always goes back in less than a day. They do grow very fast and get very large.
I have a breeding pair of managuenses in a 830 liter tank along with one black shark and three Synodontis eupterus catfish. There is also one small pleco as well as medium sized giraffe catfish. The male jaguar is approximately 33 cm long with the female being a few cm shorter. They do exhibit interesting personalities as others have commented. Mine are not aggressive at all and leave the catfish and small pleco (probably small enough to eat) alone quite well. The most aggressive fish in the tank is the black shark and the Eupterus cats (about 18 cm long). The jaguar male has exceptional coloration and prefers different food from the female. The female primarily eats Tetra Doromin while the male prefers sinking pelleted food (OSI Ocean Stars Cichlid Pellets - they're intended for the giraffe cat as he REALLY likes them).
I have 3 Jaguar cichlids. Two of them are from the wild and are 18 cm long. The other one is 25-28 cm in length. They are very aggressive. The biggest one doesn't rule my 1100 liter tank though. He bows down to my 25 cm Urophthalmus (Fake Red Terror). He is a great digger and tries to bully around my other 14 fish in the tank, except the Urophthalmus. I think he's the best looking fish in my tank too. I think the Jaguar Cichlid and the Trimac Cichlid are amongst the best looking American cichlids.
I had a jaguar cichlid for about 5 years. It lived very peacefully with my Oscar. The Oscar was about half grown when I saw the jaguar in a pet store and just had to have it! It was about half the size of the Oscar, and I was a little worried about compatibility. Sure enough, when I put it in the 200 L tank, my Oscar began to assert himself. I made a makeshift divider from a 40 L glass aquarium lid. Both fish could get past it, but the Oscar had to go through on only one side. The jaguar could pass it on either side. After about a week, the Oscar got tired of chasing, and the jaguar not being exactly shy, began to spend more and more time on the same side of the divider. Not only did they live peacefully after that, but they actually exibited affection for one another. A couple of years ago, the Oscar developed hole in the head disease. I cured it, but he was pretty ill for a couple of weeks. He would stay on the bottom of the tank, leaning over, almost on his side. For that time the jaguar was constantly at his side, actually propping him up. When I put food in the tank, she very very gently nudged him until he got moving, and went for a bite. Sadly, I lost both fish, when an ice storm knocked out my electric service. I'm going to have to get some bigger tanks and try to breed jaguars. They have got to be at the top of the list in fish intelligence, and they're the most fascinating fish I have ever known.