By Arthur Masloski (Sandtiger)
The fathead minnow (Pimephales promelas) is probably one of the most widely used fish for a number of different reasons. Aquarists will recognize it as a feeder fish, sold as “rosy reds” in their whitish/pink form. Fishermen will recognize it as a baitfish, sold all over the country. This species is also used in water toxicity tests, in laboratory experiments and as a form of mosquito control. These small cyprinids truly are a great resource. It’s their hardiness, readiness to breed and adaptability that makes them so great, both as a human tool and as one of nature’s creatures. There are various reasons why you might want to keep these fish. Maybe you have large predatory fish you want to feed (as a treat only), maybe you are looking for an easy first time breeding project or perhaps you just want to get into the hobby of keeping North American species. Though they are not bright and flashy they are certainly interesting and extremely easy.
At first glance these fish look just like any other small cyprinid so identification might be difficult. If you have gotten your fish from the wild or a bait shop it is important to identify it as the right species. Look for the following…
An incomplete lateral line
A stubby first ray on the dorsal fin, this feature is shared with the only other member of the Pimephales genus, the bluntnose minnow (Pimephales notatus).
A dark spot on the front of the dorsal fin. Another feature shared with it’s relative.
A terminal mouth, the bluntnose minnow’s mouth will be underslung.
Those are the key characteristics of the fathead. Beyond that they are rather short and stubby looking, they only grow to about 2.5”.
These guys will eat all sorts of stuff. In the wild they eat algae, plankton and small insects. In captivity they will take just about anything including flakes, bloodworms, tubifex and shrimp among other things.
These fish are used in toxicity studies so it should come to no surprise that they are hardy. The tank will not need heat of any kind, decorate the tank with plants and caves. I recommend at least a 10g for a couple pairs. For breeding a sponge filter works well, or something else that will not suck up the eggs/fry. A bit of filter floss attached to the intake on a HOB will work. For spawning caves use slate or small PVC pipe (4” diameter cut in half) to make some caves.
This is the interesting part, many people think these fish merely scatter their eggs around, this is not true, and their breeding is far more complex. To induce spawning all you really have to do is provide a 16 hour photo-period with 8 hours of darkness, this with a good diet of things like bloodworms, brine shrimp and daphnia is all it really takes. When ready to breed the males will develop a spongy pad around their head (hence the name fathead) with breeding tubercles on top. These tubercles look like small white bumps or pimples. He will also turn dark in color, almost completely black. The male will then stake out a territory. He will defend the cave and try to attract a female with the use of pheromones. He will also dance in a figure eight pattern. Once a female decides she wants to spawn with him he will lead her into the cave where they will spawn on the roof of the cave. Sometimes more than one female will spawn with a male. The male will care for the eggs, rubbing them with his spongy nape and snout in order to keep them clean. Spawning usually occurs in the morning.
What you choose to do with these is up to you, chances are the success rate will be higher is you move the eggs to another tank and place them next to an air stone. You can also keep them with the male but remove the others and remove him after they hatch. The young can be fed Artemia nauplii, Hikari first bites (or other baby fish food) and finely ground flakes.
American Aquarium Fishes Robert J. Goldstein
The Inland Fishes of New York State C. Lavett Smith