Captive Care Notes: Desert Minnows (Dionda, Family Cyprinidae)
Devils River Minnow (Dionda diaboli) are maintained by the Texas Parks and Wildlife Department in a pair of outdoor artificial stream systems designed to study the minnow's life history requirements and competitor-prey interactions with other fishes (G. P. Garrett, pers. comm.). Living in each system are other fishes that naturally occur with the minnow: Manantial Roundnose Minnow (Dionda argentosa), Texas Shiner (Notropis amabilis), Proserpine Shiner (Cyprinella proserpina), and Tex-Mex Gambusia (Gambusia speciosa). The other system is identical except for the addition of nonnative Smallmouth Bass (Micropterus dolomieu). Each system comprises six 350-gallon tanks connected by raceways to form a 2500-gallon pool-and-channel simulation of spring runs and first order streams. Water is recirculated, flowing out of the last pool into an adjoining building containing pumps, heaters, and chillers. Water is chilled in summer and heated in winter to dampen natural temperature fluctuations. The systems are unfiltered and self-sustaining, with natural growths of algae, invertebrates, and planktonic foods. Limestone rocks and native plants from San Felipe Creek and Devils River provide cover and habitat. The systems are up and running for about six months before fish are added in order to let natural nutrient recycling and biofiltration take place. Spawning occurs in the pools.
Efforts to spawn the Devils River Minnow in indoor aquaria at San Marcos National Fish Hatchery in San Marcos, Texas, have met with some success. Here about 20 minnows are placed into a recirculating system that's similar to the one above, but much smaller (about 100 gallons). Replicable propagation techniques are still being developed (J. N. Fries, pers. comm.).