Sexing
H. contradens is the same for any other
Hypancistrus including
H. zebra.
Do a forum search for sexing
Hypancistrus and you will get hundreds of hits.
The easiest way is by body shape. The male is roughly triangular shaped and has a big bulky head. His pectoral spines are thicker and are covered with odontodes. The female is fat around the middle and has a proportionally smaller head. See below
The biggest problem comes when trying to sex fish that are immature or out of condition. This is frequently the case in shops. My best suggestion is just to buy as many as you can and hope.
