These are very small crustaceans found in fresh water all over the world. The largest only growing to 1/16 of an inch long. They have no shell and 3 body parts. Their head has antennae and one eye in the center of the head. Most cyclops are transparent, though a few have color.

There are 3 main groups of cyclops. Calanoid have antennae almost as long as their bodies and line in plankton. They feed on filtered organic matter. Cyclopoid have antennae as long as the main part of their bodies and live in open water. They seize and bite small prey. Harpacticoid have short antennae and live in silt and plant debris. The feed by scraping algae and detritus from rocks and other objects.

Cyclops reproduce sexually. The females then carry eggs in sacks that hatch in about 10 days. The larva develop in 3-4 weeks.

Below is an old article I wrote in 1997 about raising gammarus as live food. I used them to feed bumblebee gobies. I used to have a lot of gammarus and eventually stopped paying attention to them, stopped using them as a live food, and thought they would be around in my tanks forever since many of my tanks had a colony in them. I've realized lately that I don't seem to have any left.

Raising Gammarus

I keep the Gammarus I feed my bumblebees in two five gallon buckets. These are the standard restaurant type buckets. I don't heat, aerate or filter these buckets in any way, however I do keep my fish room pretty warm, and I haven't seen them get below 72 degrees.

I feed the Gammarus on cuttings from plants in my tanks. They also will eat hair algae. Whenever I get any in a tank I pull it out and feed it to my Gammarus.