Most often found in hobby literature under the "old" genus Cichlasoma, Heros severus is an old timey favorite of cichlid lovers everywhere. And as the title above denotes, there are more than one "Severum". Of the four currently recognized species of the genus Heros, (H. fasciatus, H. spurius, H. notatus (fishbase.org) only H. severus occurs in the trade regularly, in both wild and golden xanthic color forms. "The" Severum has been an aquarium "standard" since its inception into the hobby in Germany and the U.S. in the early twentieth century.
Though often haphazardly placed with other freshwater fishes, this South American often suffers from being placed in water that is too cool in temperature, and too hard and alkaline in chemistry.
Some writers have declared that Severums are aggressive in nature. I would encourage these same folks to try placing their fishes in adequately large settings. Breeding pairs should be kept in at least a hundred gallons, small communities of this species in at least twice this gallonage.
Severums that have been bred in captivity for successive generations (as opposed to recently wild-caught specimens) can do well in most tap waters of moderate hardness and neutral pH. However, they are best bred in softer, more acidic water that approximates their natural waters (see above). Water motion is best dissipated with the use of spray bars in the case of canister filters and slower, more numerous numbers of smaller hang on filters if used. This fish "hangs out" under substantial floating plant cover in stiller waters in the wild.
Though not overtly digging monsters like many neotropical cichlids, Severums do eat a bit of plant material in the wild, and may well do the same to softer species in your tanks. If you use live plants, try the tougher (non-indigenous to South America) varieties of the genera Anubias or Cryptocoryne... or the ever-popular Plasticus floribunda, polyethylene plants. Rockwork and sunken driftwood are definitely appreciated by Severums, and useful for limiting aggression and serving as spawning media.
Best kept with fishes that enjoy the same type of water conditions, and about the same size. Severums can be housed with Festivums, Acaras (Aequidens species), Eartheaters, many types of Loricariid and Callichthyid catfishes, even large angels and dwarf cichlids when young.
As previously mentioned, Severums are partly herbivorous. Some home-grown lettuce, green peas or zucchini that has been blanched or microwaved can be offered, oriental algae-based foods, or dried-prepared foods of plant origin. Beef heart and liver are not suggested for Heros as they have a hard time digesting these fatty foods. Given the various food formats, pelletized and "stick" foods are preferred by most large cichlid keepers. These are readily available and cheap (especially in bulk), and make for the least amount of wastes and their by-products. An occasional earthworm, mealworm, bloodworm or marine crustacean offering is much appreciated.
Breeding pairs are best developed through the raising of six or eight young together. Even at relatively young, small size Heros severus may be sexed by the absence of markings on the gill covers and smaller body size of females. Pairs should be either housed with other Severums (in a large enough system for two or more territories), other cichlids of equal aggression and size, or at least some fast, aware ditherfish, to reduce intraspecific and pair aggression. "Making" pairs from adult fish is not easily done, best to raise a group together and let them sort each other out. Males of this species are decidedly larger with prominent nuchal humps. Many commercial breeders utilize dividers that the pair can see each other, but not get to each other, to accommodate fertilization w/o risking loss of the adults from fighting.
For proper hatching and development, softer, more acidic and tropical water is required. Though the serially tank-bred specimens will tolerate pH's approaching 8.0 and 300 ppm of total hardness, and temperatures in the seventies F., conditions of pH in the 6's, up to 50 ppm total hardness maximum and the mid to upper 80's are best for breeding.
Heros are partial or delayed mouthbrooders. After hatching, the young are taken into the parents mouths. Periodically they are released to hunt for foodstuffs that can include freshly hatched brine shrimp, ground flake or pelleted foods. Most pairs of Severums prove to be good parents.
Severums are one of the most sensitive freshwater fish species to the ill-effects of diminished water quality. Head and lateral line disease is often evident (neuromast destruction) in specimens that have been kept in water of too high concentration of dissolved organics. Undercrowding, sensible feeding, sufficient biological filtration and maintenance procedures (particularly frequent, partial water changes) can/will preclude this problem.
Though probably not considered a "disease" per se, this is a "nervous" species of fish that is quite capable of damaging itself, even jumping out if disturbed. Endeavor to make slow movements, gradual increase/decrease of lighting in and around their system, and do provide a secure, complete cover to prevent jumping.
The damage from handling and shipping this fish often results in ich and "fungal" fin rot (actually bacterial) infections. These respond well to TMC in addition to chemical protocols.
An old-timey favorite for good reasons, the Severum is a good fish for folks with lots of space, easygoing tankmates and possibly a need for hobby-supporting income. Consider a large (1-200 gallon) system for maintaining a breeding pair and the accessory tanks, space for rearing their young.
Bailey, Mary. 2001. The Severum. Large, but basically a pussycat. AFM 8/01.
Leibel, Wayne S. 1993. A Fishkeeper's Guide to South American Cichlids. A splendid survey of this attractive and diverse group of freshwater tropical fishes. Tetra Press, Blacksburg, VA.
Leibel, Wayne S. 1995. Festivum... Severum, Severum... festivum- an introduction. AFM 12/95.
Loiselle, Paul V. 1985. The Cichlid Aquarium. Tetra Press, Melle Germany.
Loiselle, Paul V. 1994. The Severum. An old friend revisited. AFM 9/94.
Schiff, Steven J. 1994. Aquarium fish profiles: the Severum. FAMA 6/94.
Schmelzer, Gunther. 2001. Heros severus: An old friend. TFH 3/01.