Medium to large Cichlids have, in general, a reputation of aggression towards tankmates, intolerance to others of their kind, and just a bad attitude in the aquarium.

To dispel those myths, in this post we'll study what I call the mellow fellows; that is, the medium to large Cichlids that, to a lesser or greater extent, are completely passive in the aquarium. Some, of course, are more passive than others, and one or two can suddenly turn from Dr. Jeckle to Mr. Hyde in an eye blink, or will stay mellow throughout their life. For this post, I'll define medium as fish that grow to over four inches in total length, though most in the list get a good deal larger than that, and are gentle to tankmates too large to eat.

Some species in this list are ridiculously easy to find in shops, some with take some searching, but all are well worth dedicating tank space to. Keep in mind, though, that they are Cichlids, and thus can be unpredictable, but of course, the ones in this list are easily defined as passive in the aquarium.

Now, some species.

By far the most common and popular mellow fellow available is the Oscar (Astronotus ocellatus), of soft, acidic tributaries of the Amazon basin in Venezuela, Guyana and Paraguay.

Oscars, which reach 14 inches given the time and space to do so, are affable to fish too large to eat and to each other when kept in a group, if introduced all together when young. And they have, for lack of a better word, personality. They very quickly learn who feeds them, and they will do all kinds of antics to get the attention of their keeper.

A favorite is a tail slap on the surface of the water. Some jump clear of the water, landing with a huge splash. Another is the whole group at the front of the tank staring at you until you feed them. Redesigning the tank decor when things don't go their way is common. A stomach with fins, Oscars are always prepared to eat, and if you're not careful, they'll train you when, what and how much to feed them with their behavior.

In nature they live in both black and white water habitats that are quite soft and acid, even down to pH 5.5 with near zero hardness. Commercially bred for decades, they'll even live and possibly breed up to perhaps pH 7.5 with moderately hard water. However, they live and breed best in the soft and acid tank, as eggs usually don't hatch in hard water. They prefer temperatures between 75 and 80 degrees. Filtration through peat moss darkens and softens the water, which usually triggers breeding in this species.

Captive breeding has resulted in many different color morphs. Primarily it's red and orange markings on a black or dark grey-green ground, usually with an occelated orange or red circle (the 'ocellatus') at the top of the caudal peduncle. Some can be almost totally orange, some albino with light orange markings on an ash-white ground. There are dozens if not hundreds of color variations of this species. And each Oscar is as individual as a fingerprint; no two are exactly alike in markings.

If you wish to breed or just keep a group of Oscars, a 200-gallon tank would be sufficient for a group of six or eight adults. It should be furnished with just driftwood and stones, as live plants would be pointless, as they always tear them out. In larger quarters, tankmates can be schools of larger Characins, like Silver Dollars, or Cypranids like Tinfoil Barbs; in other words, schooling fish that grow too large to eat. Catfish can be the Doradids, who are so well armored even an ever- curious Oscar knows better than to touch them. Some of the larger riverine Synodontis would be OK, just make sure they grow to at least six inches. One or more of the sucker-mouthed cats (plecos) can take care of algae duties. Make sure the species grows to five inches or more.

Stay away from pictus cats and the like, because the long whiskers irritate sleeping Oscars, and as Oscars have long memories, they'll eventually kill the pictus because of that irritation. A dark substrate and background intensifies the colors of Oscars.

The larger the tank the larger and more entertaining Oscars get. In feeding, if you give it to them, they'll probably eat it. A very omnivorous fish, high-quality pelleted foods can be staple, and they like things like fresh spinach leaves, small shrimp (either live or frozen), clean live red worms, California black worms, pieces of apple and pear . . . in other words, they will eat what you give them, so make sure the quality is a high as you can make it for their continued health and vitality. Though they can be picky towards foods, their stomach will win out every time if you're persistent with foods that are good for them.

As an aside, don't feed Oscars live fish, as they are too rich for the Oscars' systems, eventually causing kidney shutdown and death. Properly kept, Oscars easily live well over 20 years.

In breeding, juveniles pair off early, and stay mated for life. Best bet is to buy eight youngsters, and select the most compatible pairs for transfer to the main tank. Oscars are flat rock spawners, and full-grown adults can lay more than 2,000 eggs. Excellent parents, the vast majority, easily 90 percent, of the fry will survive and thrive under the adults' care.

If you aren't concerned with breeding, a good-sized group of Oscars in a large aquarium is an endlessly entertaining sight.

On to Part 2