Introduction to Thorichthys

(This article was originally published in Cichlid News magazine, Aquatic promotions, Vol. 2. No. 1, January 1993; pp. 14-15. It is here reproduced with the permission of Don Danko and Aquatic Promotions).

Of Regan's five sections of the genus Cichlasoma , one stands out as having the best combination of a smaller size and excellent coloration, thus being ideally suited for aquarium habitation. That section is the Thorichthys species group, a closely-related group of Middle American species named by Meek in 1904, who originally regarded the group as a distinct genus, but later in 1907 relegated it to a subgenus of Cichlasoma. Recent thoughts are again that it may deserve generic status (Kullander, 1983; Heijns, 1992); however, in this article, Thorichthys will be considered a species grouping, the position taken by Miller and Nelson (1961) (E.N. Thorichthys is now considered a genus, 1996. This article will provide an overview of this group focusing on differences between this and other species groups, natural habitats and tank maintenance, as well as color plates picturing several of the group's members.

What differentiates Thorichthys from other Cichlasoma species groups, you might ask? Miller and Nelson (1961) report nine distinctions from other groups, the most noteworthy of which to tropical fish hobbyists are: (1) a tendency toward a lunate (=half-moon) caudal margin frequently with filamentous extensions; (2) a prominent black spot on the lower portion of the gill plate; (3) the anterior portions of the fish usually adorned with blue spots; and (4) a reddish gill region. These features, in addition to an adult size of less than seven inches, readily differentiate Thorichthys from other Cichlasoma groups.

Members of the group typically inhabit rivers and lakes. From collecting experiences in the Rio Papaloapan and Coatzacoalcos systems in México, I have found that Thorichthys species tend to inhabit shallower portions of rivers and are most frequently found in smaller streams. It is very common to find them in areas laden with submerged branches which provide territories for pairs engaging in spawning activities.

Most Thorichthys species rarely exceed five inches in total length, and all exhibit outstanding coloration. In addition to pleasing reds, blues, and yellows, the flanks usually have metallic reflectivity, all contributing to an attractive appearance. As mentioned earlier, the combination of a smaller size and attractive colorations makes Thorichthys species outstanding candidates for aquarium habitation. Large tanks are not required, as a compatible pair can be successfully housed in as little as a ten gallon tank. They can also be set up in community tanks of compatible species in forty gallon aquaria and larger. As a result, they are good choices for hobbyists with limited tank space still interested in Neotropical cichlids. Tank maintenance is not difficult as long as the nitrogen cycle is managed; as with many cichlids, ammonia is not well tolerated. Problems manifest themselves in a loss of appetite, white stringy feces, and eventually a swollen abdomen ­ all classic signs of "bloat." The best medicine is prevention by a light tank stocking and frequent partial water changes. Once contracted, however, metronidazole is the treatment of choice.

Thorichthys species are not picky eaters with most live, frozen, and prepared foods accepted readily. One of the few foods not taken is plant material. To avoid redundancy with other previously written articles, suffice it to say that spawning is in typical substrate-spawning cichlid fashion. Spawn sizes can range from as few as 25 to a few hundred, depending on the size and species. For additional details on spawning behavior, see Calhoun (1991) and Danko (1990).

Ten species of Thorichthys are now recognized, all from the Atlantic slope of Middle America, as listed in the accompanying table. While these are recognized in the cichlid literature, it is interesting to note that extreme variation in color is found when one observes and collects in the wild. For example, in the Rio Papaloapan, I have noted three distinctly different color morphs of T. ellioti. In the westem tributaries near Jalapa and Veracruz, T. ellioti is stocky and very red. In the central portion of the system at the Rio Obispo, individuals tend to have a bluish cast with a rose-colored belly. In the eastern reaches, T. ellioti are much more yellow-gold with a red-orange belly. Even the shapes are noticeably distinct, so that although treated as one species in the literature, they represent visibly different animals. This is likely to be the case for other known species in other river systems.

Hopefully, this brief summary on Thorichthys has piqued your interest relative to these colorful and easy to maintain animals. Their beauty, size, advanced behavior, and compatibility make them ideal additions to any collection of aquarium fishes.

References Cited

• Calhoun, ; 1991. Cichlasoma ellioti, a love story... of sorts. Bul. Cich. Study Group, Amer. Cich. Ass'n., vol. 10(2):8-9.
• Danko, ; 1990. Observations on Cichlasoma aureum Bul. Cich. Study Group, Amer. Cich. Ass'n., vol. 10(1):34.
• Heijns, W.; 1992. The Cichlasoma saga: the rise and fall of a cichlid genus. Bunt. Bul. 149:4-16.
• Kullander, ; 1983. A revision of the South American cichlid genus Cichlasoma (Teleostei: Cichlidae). Stockholm.
• Mayland, ; 1984. Mittelamerika, Cichliden und Lebendebarende. Lanbuch- Verlag Gmbh, Hannover.
• Miller, R. R. and B. C. Nelson.; 1961. Variation, life colors, and ecology of Cichlasoma callolepis, a cichlid fish from southern México with a discussion of the Thorichthys species group. Occ. Pap. Mus Zool., Univ. Michigan, no. 622:1-9.
• Stawikowski, R. and U. Werner. 1985. Die Buntbarsche der neuen Welt. Mittelamerika. Reimer Hobbing Verlag, Essen.