9715

• UCREFRP Catalog Number: 9715
• Author: Ward, D.
• Title: Removal and quantification of Asian tapeworm from endangered cyprinid fishes using Praziquantel.
• USFW Year: 2005.
• USFW - Doc Type: Arizona Game and Fish Department.
• Copyright Material: NO

Results

Laboratory evaluations. - No mortaUty occurred at any of the Praziquantel concentrations

used in our laboratory tests, indicating Praziquantel dosages of up to 36 mg/l are safe for use on

bonytaiL No fish showed signs of stress or loss of equilibrium. One month post treatment there

were no significant differences in fork length (P> 0.82) or weight (P>0.29, two sample t-test)

for fish exposed to 36 mglL Praziquantel dosage, when compared with controls, indicating a 24-

h exposure of up to 36 mglL did not have delayed impacts on growth of bonytial chub. Dosages

less than 1.5 mglL and durations of treatment less than 24-h were ineffective at removing 100%

of tapeworms (Table 3). Infected fish showed no differences in weight gain or growth when

compared to control fish 20 days after infection with tapeworms. Cole et aL (2004) also found

no impacts on growth or physiological condition in laboratory infected fish. This may be

because fish were fed ad-libitum throughout the study and tapeworm loads were small.

The percentage of tapeworms that were successfully transferred from red shiners into

bonytail chub was variable ranging from 2 - 63% (Table 2). Larger fish appeared less

susceptible to infestation with tapeworms after manual transfer from another host. In pilot trials

using 24 infected red shiners (Cyprinella lutrensis) and 6.0 mglL Praziquantel, differences in the

amount of alcohol used (0.35 ml alcohollL of water compared with 1.44 ml alcohol/L of water)

did not affect the speed at which tapeworms were evacuated from the host (P>0.48). Red

shiners exposed to the highest concentrations of alcohol were sluggish but did not die indicating

high doses of isopropyl alcohol were also safe for use when treating fish.

There is suggestive, but inconclusive, evidence that high doses of Praziquantel cause faster

evacuation of tapeworms from bonytaiL Comparison of evacuation rates for low (0.7mglL)

versus high (36 mglL) dosages ofPraziquantel were significantly different after 12 h of

treatement (P> .04) but were not different after 24 h (P>.26) (Tables 3 & 4).