Sexing frontosa is typically difficult at best, even for the experts. I have seen exporters, importers, breeders and aquarists sex frontosa incorrectly. It's not that it can't be done, but it can be difficult.

There are several indicators that point to the sex of a frontosa. None of these points can be used until the fish are at least three inches, in my opinion.

1) Behavior- If one has ample time to observe a group of frontosa in a aquarium, there is a chance to sex the fish just on observation. This is especially true if the group had grown up together or at least has spent enough time in a particular aquarium to feel comfortable.

When a group of frontosa is grown up together in a group of six or more, it is almost guaranteed that the largest specimen is a male. Males generally grow larger then females and grow more quickly. A male must fight aggressively to become "king" of the harem. A larger fish has a better chance of being dominant thus the largest fish in a group is a male. If that male is removed from the group, a subdominant male will have a growth spurt and take his place.

Quite often a new hobbyist will believe that out of his group of frontosa, the largest is a male and the rest are females. While this may be the case, most likely it is not. Subdominant males may remain small because they have to in order to avoid the dominant male's wrath in the aquarium.

Males will also show aggression towards males and try to court females. You must watch carefully and patiently for a male frontosa to show his courting dance. It consists of the male listing to one side slightly while folding his fins. This may be followed by a slow sweeping circular motion over the substrate of the aquarium. It is a gentle gesture and is much harder to spot then many of the rift lake cichlids.

Often, sellers of frontosa groups have a more then optimistic idea of how many frontosas in a group are female. Buyer beware!

2) The nuchal hump- The hump on the head of the frontosa is actually an extension of the dorsal muscle. While there is no doubt that large older dominant males can have enormous humps, it is by no means a definite indicator of sex. I have seen females with large humps many would swear are males. I have also seen males that have a hardly any hump at all, many times there were subdominant males. All adult frontosas have a hump to some degree.

3) Venting or tubing- "Venting" or Tubing" actually involves viewing the sex organs of a fish in order to determine sex. This procedure is the most reliable method to sex frontosa, with practice. Larger specimens are easier to sex then smaller specimens. I personally have a hard time sexing a frontosa by venting, if under four inches. Frontosa that have already spawned are also easier to vent as it seems that when a female passes eggs her tube becomes larger.

In the photos below we can see pictures of confirmed male and female frontosa. There are two holes on each fish. The one towards the top is the anus. The one towards the bottom, closet to the anal fin, is the sex organ. You will notice that the female sex organ is more rounded and the male is more triangular. Trust me, it gets easier with practice.

Some individuals may be harder to sex then others. The male pictured below is a decent example but, I have seen others that were much easier to sex. The sex organ of the some other males I have vented were narrower and more triangular in shape. □

Female Frontosa	Male Frontosa