For the beginning aquarist, identifying unknown Crenicichla species can be confusing and difficult. The first course of action is to ask other hobbyists or look up reference books. The Cichlids Yearbook series, the German book on South American Cichlids, Die Buntbarsche der Neuen Welt by Stawikowski and Werner and the Aqualog South American cichlids 1 can be reasonably helpful in pinpointing the identity of a species.
The description of the physiology and appearance of a species in question are powerful tools in identification as well. Once you get comfortable with the terminology used in technical literature, you will be able to break down the fish into a set of unique physical traits.
The following are descriptions of a few physical characteristics that may help you:
Suborbital marking: This refers to the marking immediately under the eye. Most Crenicichla species groups have suborbital marking unique to them, of course, with a few exceptions. These markings are usually triangular or striped and some species do not have any. The triangular markings are common in the saxatilis group. C. semicincta from Peru of the saxatilis group is an exception, it has a sub orbital stripe. Most Froghead Pikes of the reticulata group and dwarf pikes of the wallaci group do not sport suborbital markings. The old lepidota group sensu Kullander and the coastal species of the lacustris group of Eastern Brazil, have sub orbital stripes. It must be mentioned that these species groupings are not very distinct and the generalizing based on their occasionally overlapping boundaries should not be followed rigidly. However, discussing it, rather than not, is mildly educational.
Postorbital marking : This refers to the marking between the eye and the operculum or the gill cover. Some species like C. lugubris have a black blotch there. C. proteus have a simple horizontal black line there and female C. frenata from Trinidad have a black line sandwiched by two whitish lines.
Humeral blotch: This is the dark blotch immediately behind (posterior) and slightly above the operculum. It is absent in the reticulata, lacustris and wallaci groups. It is prominent in the lugubris and saxatilis groups. These blotches may vary in size and may or may not be ocellated (surrounded by a light colored ring.) The position of the humeral blotch relative to the lateral line is an important identification tool. The lateral line cuts through the middle of the humeral blotch in some species and in others the blotch is clearly beneath the lateral line.
Dorsal ocelli: This refers to the dark or black spots/blotches on the dorsal fins of the females of some species. This trait is particularly evident in some C. regani forms, C. notophthalmus, females of some lacustris and some reticulata group members. Like the humeral blotch, these spots may or may not be ocellated.
Submarginal band: This trait is mentioned in reference to the light colored (often white) line just below the outer edge of the dorsal fin in females. This band is usually broad and red in females of the reticulata group. Usually lacking in some dwarf species and the lacustris group.
Caudal ocelli: Like the dorsal ocelli and the humeral blotch, the caudal ocelli is a “false eye” that many South American cichlids use as a deterrent against small fin-nipping Piranhas that are less likely to attack the region around the eye of the prey. This spot is located at the base of the tail. Again, it varies in shape, size and degree of ocellation.
Fin ray counts (meristics): This ichthyological tool is also a good identification tactic. All cichlids have a range of hard and soft fin rays. I have used the dorsal fin rays to narrow down some species identification. With live aquarium specimens, this is difficult but it is possible with a crisp and clearly lit photograph. Netting the fish our and actually counting the rays is slightly more traumatic and stressful to your charges. The numbers may then be compared to published figures.
Extension of Maxilla under the orbit: Pike cichlids, often with their wide gapes, have the ends of their lip fold or corner further back than most cichlids. This extension of the lip goes back as far as just below the eye or sometimes farther. In some species, the corner of the lip does not extend as far back as the eye. This is a species or group specific trait.
Placement of nostril relative to the labia: This is the space between the edge of the lip fold and the nostrils. In some species like C. reticulata, this distance is very short. There is a species determined distance between the two points.
Longitudinal scale count This is an ichthyological tool, usually used to distinguish between the aforementioned groups of pike cichlids. This is a number, often a range, of scales along the longitudinal length of the fish. Strigata group members have a high number of scales (often around 100) while C. britskii has low figures, about 45. This is not a practical instrument of pike cichlid identification.
Morphometrics This is the information derived from the body proportions of the fish, like the height of the fish given as a ratio to the length of the fish.
If you find yourself reading some of Kullander’s or Ploeg’s publications, you are likely to run into a few more words that you may not be familiar with. Their papers, especially Kullander’s, become enjoyable if you understand some of the terminology used in describing a species.
Holotype: a single specimen of a species used for describing the species. If many specimens are used for the descriptions, a single specimen is usually identified as the holotype.
Paratypes: if a holotype is specified in a description based on many specimens, all the fish other than the holotype are paratypes.
Syntypes: often in older or in insufficiently detailed descriptions a holotype may not be specified. Worse, it may be “lost” or not stored in a museum. In such cases, similar specimens are set up as syntypes. This process leaves room for errors in the author’s interpretation.
Lectotype: if a previously described species is examined at a later date by an ichthyologist, a lectotype may be chosen from among the type series to be used as a defining specimen.
Of course, this is by no means a comprehensive list of technical jargon used in pike cichlid nomenclature, but it is hoped that learning this vocabulary will make your next trip to the library a little more productive. If you have read this far without falling asleep, my hat's off to you. Here's a tongue-twisting brain teaser just for you: what are the meanings of the terms proteropolyspondylous and opisthopolyspondylous? If you know, email me at kutty at earthlink dot net.