How can I tell the sex of my Oscar Fish?


- Submitted by Saluki

One of the most common questions asked on this site is how to tell whether an Oscar is male or female. Unfortunately, there is no easy answer. Many people who are new to oscars, and even some experienced oscar keepers will come up with various “surefire” ways to sex an oscar. These methods are usually based on some minor differences in finnage, color, spots, shape, size, etc. Unfortunately, none of them are any more reliable than flipping a coin. The bottom line is that Oscars, unlike most other cichlids, exhibit no external sexual dimorphism. In other words, you cannot tell the sex of an Oscar by any external features.

So, you ask, how can I tell if I have a male or a female? Well, the only reliable method is to observe a pair when they are breeding and the breeding tubes are extended. The female's tube is bigger, and rounded at the end, while the male's tube is smaller, and pointed at the end. Also, obviously, the female is the one with all the eggs coming out of her. Note that it is not uncommon for two female Oscars to pair up and mate together. In this case, both breeding tubes will look the same, and both will have eggs coming out. Also, the unfertilized eggs will be white in color. Fertilized eggs are amber (yellow) in color.

Sorry folks, the short answer is you will never know the sex of your Oscar unless/until you see him/her spawning, or if your solo Oscar lays eggs.