Captive Care Notes: Creek Chubs (Semotilus, Family Cyprinidae)
Semotilus do well in aquaria if given sufficient space and food. Inadequately fed specimens may live a long time but tend to look emaciated. Semotilus accept all aquarium fare and are not shy about nibbling a fishkeeper's hands when they enter the tank. As surface feeders they tend to jump, so a tight-fitting cover is required. They're peaceful with other fishes too small to swallow.
Most aquariums and aquarium-kept Semotilus are too small to induce spawning, but it's possible with larger specimens. According to American Aquarium Fishes, spawning Creek Chub (S. atromaculatus) in aquaria requires collecting two nuptial males and 2-4 females from the wild at the beginning of their spawning season. Place them into a long 40-gallon aquarium (or larger) outfitted with powerheads for current and a pea gravel substrate. Feed the chubs heavily on live and prepared foods, including blackworms and crushed snails. Should spawning occur remove the adults. Eggs hatch in 4-6 days. According to Buynak and Mohr (1979), Creek Chub and Fallfish (S. corporalis) larvae will feed on live brine shrimp and powdered dry commercial fish food. As the larvae grow they can be weaned over to a more granular prepared food.
Commercial bait breeders spawn Creek Chub in large artificial raceways that empty into pools. The raceway provides the spawning area (running water over gravel), and the pool acts as a refuge for adults and as a collecting basin or rearing pond for the newly hatched fry. Splash boards installed in the raceway create riffles and prevent the pool from being filled by washing gravel. The raceway is stocked with wild-caught specimens measuring no less than 15 cm (6 in) for males and 13 cm (5 in) for females. A uniform size among males is preferred since larger males will badger and kill smaller ones. Stocking density is one female per every 1.5 square feet of spawning area. Females should outnumber males by 2:1 or 3:2. Fish should be stocked into the raceway when spawning is occurring nearby in the wild, or when the raceway's water temperature has reached 13C (55F) for at least two consecutive days. Each female can produce 400-800 fry, which tend to school in large numbers near the surface along the shore of the refuge pool. Removing the fry to a separate growing pond increases their survival. During the first six weeks of life Creek Chub fry eat a fine-grained prepared food. Growth is rapid. By the end of six weeks the fry will have reached 4 cm (1.5 in) in length, whereupon they should be switched to a pellet-sized food. Care must be taken not to overfeed in order to maintain water clarity.