Determining the sex of fish seems to be a very popular question. This is not always as easy or reliable as one might hope; nothwithstanding, there are several techniques for determining a fish's gender.

If your fish are dimorphic (i.e., males and females have distinct coloring patterns), the task will be rather easy. All you need to do is find pictures of both the male and female for your species, and then simply compare. Sometimes fish that are dimorphic have very subtle differences and distinguishing them can be difficult, and may not always be apparent. In this case, solving the mystery of gender for these fish should be addressed as if they were monomorphic (i.e., males and females look similar).

Determining the gender of monomorphic species requires a process commonly called "venting."This involves removing the fish (with wet hands) and examining their dorsal side, looking for the genital pore between their anus and anal fin. As these twopictures demonstrate, the more anterior pore is the anus, while the second pore is the genital papilla, or vent. The genital papilla (also called an ovipositor for females) is the pore through which the fish will excrete either eggs or milt.

Generally speaking, females will have a larger genital papilla than their male counterparts. This larger size is needed to accommodate the passage of eggs. This difference is more difficult to distinguish for substrate egg layers (e.g., Neolamprologus spp.) because their eggs are smaller than those of female Mouthbrooders.

There are some cases where certain species demonstrate pigment differences between the male and female vent. And with some species, males will have an elongated and tapered genital papilla, such as the Julidochromis regani. With these males you can move your finger across the vent region from left to right and the genital papilla will also move.

When venting your fish, be sure to handle the fish only with wet hands. I have found that grabbing them with a net gives me a little extra grip so that they can't slip out of my hands. Also be sure that you do not keep them out of water for more than about 30 seconds. You want to make this as un-stressful as possible, so try to keep the number of times you examine them down to no more than 3. Once you have sexed your cichlid, you will want to keep it separate from other un-sexed cichlids. Think about how you are going to address this before you start handling them.

There are other methods aquarists use to sex their cichlids, albeit less reliable. Some of these include noting behavioral differences, size differences, body and fin shape differences, as well as the presence of egg spots. Most male Mouthbrooders have at least one egg spot on their anal fin, if not many more than this. Unfortunately, there are only a handful of species where males exclusively have egg spots. Many females also commonly display at least one egg spot. This fact makes relying upon the presence or absence of egg spots unreliable at best, but it can still be helpful, as males tend to have more egg spots than females of the same species. Note this is a broad generalization.

Another "shotgun" method is relying upon body size, as males are often larger than females. And then with some species, particularly Lake Malawi species, fin shape is a somewhat reliable method for determining gender. Below I have posted pictures of wild pair of Auloncara hansbaenschi. A difference can be seen by looking at the most posterior portion of their dorsal fins. Males' dorsal fins end with an exaggerated point, while females' dorsal fins end with a rounded curve.

The only sure way to determine the gender of your African cichlid is to examine their vent region. Sexually mature adults are, of course, easier to sex, but with experience you will soon be able to determine the gender of most species at as early as four months of age with a high degree of accuracy. Aquarists familiar with a particular species often rely upon some of the differences we've just discussed even though these are not fail-safe. Again, venting is the only sure way to determine your fishes’ gender. □