Some Potential Fish Health Concerns for Threatened and Endangered Species and Other Fishes in the Upper Colorado

Home Browse Search

CDOW -BRUSH TEL No.303 -842 -2849 Apr 10,92 14:09 No.003 P.03 j_ PAGE 2 - UPPER COLORADO T &E FISH HEALTH CONCERNS mottled sculpin (Coitus balydi) , has been observed to be involved in these outbreaks. However, virtually any fish species is potentially vulnerable, especially if environmental conditions are poor and other sick or carrier fish are present. (A salmonlcida was recently isolated from symptomatic white suckers in the Fort Collins area on the East Slope.) The potential of Basin T &E species to be them- selves carriers of A. salmoniclda is unknown, but it must be assumed to be possible. Among the opportunistic environmental bacteria that frequently cause disease in fishes are the Aeromonas hydrophlla complex (Motile Aeromonad Septicemias) and various Pseudomonas species (Motile Pseudomonad Septicemias) as well as many members of the family Enterobacteriaceae. PROTOZOAN PARASITES Many of the protozoan ectoparasites have broad host ranges and are considered virtually ubiquitous in distribution. Under the right circumstances, nearly every type can cause fish health problems. The flagellate Ichthyoboda and the ciliate Ichthyophthirlus multifilils have been particularly frequent and severe in Colorado fish culture in recent times. Several chemicals have FDA or EPA clearance for use in controlling external fish parasites and are useful in treating cultured fishes. Wild epizootics of protozoan ectoparasites are seldom recorded, although they may simply go undetected in the majority of cases. However, an epizootic of Ichthyophthirlus in feral white suckers and minnows was reported in a West Slope pond by John Riger in 1989. SROROZOAN PARASITES The majority of sporozoan parasites of fishes are not only very histospecific (infecting only a certain type of tissue) but highly host specific as well. There is no information on sporozoan species in Basin T &E species. No sucker or minnow species are believed susceptible to Myxobolus cerebralls, the infamous agent of salmonid whirling disease. METAZOAN PARASITES In his book Parasites of North American Freshwater Fishes (Univ. of California Press, 1970) Glenn Hoffman cites no records of parasitology work having been done on any of the Basin T &E minnows or sucker. How- ever, Hoffman does list the following parasite species totals for members of the same genera: Sacramento squawfish (Ptychochellus grandis) Trematoda 4 Cestoda 1 Nematoda 1