9706

• UCREFRP Catalog Number: 9706
• Author: Ward, D.L.
• Title: Removal and quantification of Asian tapeworm from bonytail chub using Praziquantel.
• USFW Year: 2007.
• USFW - Doc Type: North American Journal of Aquaculture
• Copyright Material: YES

208
TABLE l.-Praziquantel dosage, volume of alcohol added,
fish length, and total number of bony tails used in praziquantel
bath experiments, Rocky Mountain Research Station.
Praziquante1 treatment
Isopropyl
Dosage Duration alcohol Number Mean (ranges)
(mg/L a) (h) added (mL) of fish total length
0.7 12 12.5 12 152 (130-179)
0.7 24 12.5 12 145 (121-166)
0 12 12.5 12 153 (124-178)
0 24 12.5 12 151 (139-178)
1.5 12 25 12 145 (127-168)
1.5 24 25 12 147 (137-155)
0 12 25 12 148 (138-162)
0 24 25 12 142 (128-152)
6.0 12 100 12 145 (131-159)
6.0 24 100 12 146 (128-162)
0 24 100 12 150 (138-159)
0 12 100 12 143 (126-161)
6b 24 100 9 403 (370--457)
Ob 12 100 3 378 (373-382)
36.0 12 600 12 146 (129-165)
36.0 24 600 12 146 (132-165)
0 12 600 12 149 (136-173)
0 24 600 12 146 (129-166)
a 0 mg/L = control.
b Adult.

Rocky Mountain Research Station in Flagstaff, Arizo-
na, where they were dissected. Live Asian tapeworms
were removed from the red shiners and manually
inserted down the throat of 105 treatment bony tails
(110-457 mm total length [TL]) to produce a group of
known infected fish for testing. The bony tails used in
these tests were designated for research purposes
because genetic constraints would not permit them to
be released into the wild. These fish were known to be
free of Asian tapeworm before the study. The Asian
tapeworm load from one red shiner was inserted into a
single bony tail to replicate a natural infestation rate.
Natural fish populations typically have highly variable
incidence of Asian tapeworm infection, so no attempt
was made to standardize Asian tapeworm infection in
each fish. Bony tails were held for 20 d after infection
to allow the Asian tapeworms to become established in

WARD

the new hosts. Groups of 24 bony tails were then treated
with one of four dosages of praziquantel (0.7, 1.5, 6.0,
and 36.0 mg/L) for two different time durations (12 and
24 h) and 12 fish in each time treatment (Table 1). Nine
larger bony tails (370-457 rnm TL) were also treated at
6.0 mg/L to evaluate mortality and side effects of
praziquantel on large adult fish. The limited number of
adult bony tails available only permitted experiments on
adult fish to be conducted at one dosage of praziquantel
(6.0 mg/L).
Praziquantel is soluble in alcohol and only slightly
soluble in water, so the required dose of praziquantel
was dissolved in a small volume of 70% isopropyl
alcohol at a rate of 1 mg/16.7 mL of isopropyl alcohol
before adding it to the treatment water (Table 1). All
treatments were performed in aerated, 1.S-m-diameter
tanks with 454 L of water at 20-220C. Each treatment
group had a separate control group consisting of the
same number and size of fish. The control fish (n = 99)
were handled identically, except that no praziquantel
was used.
Fish were treated by placing them individually into
ll-L perforated buckets or 76-L plastic totes (depend-
ing on fish size) within the holding tank. These
receptacles were perforated with slots on the sides but
not on the bottom, allowing water movement through
the container while still retaining the evacuated Asian
tapeworms from each individual fish. Two air stones in
the bottom of each holding tank provided water
movement and aeration within the treatment tank. I
covered the treatment receptacles with a screen to
prevent fish from jumping out. After treatment, half of
the experimental fish were dissected immediately and
the number of Asian tapeworms in each fish was
recorded. The other half of the treated fish were held
for 30 d in freshwater to evaluate delayed effects of
praziquantel use. After 30 d, these fish were also
dissected and the number of Asian tapeworms
remaining was recorded (Table 2). These tests were
designed to evaluate nonlethal methods for quantifying
Asian tapeworm loads in individual fish and to identify

TABLE 2.-Number of Asian tapeworms initially inserted per fish, number of tapeworms removed per fish,
and total number of tapeworms inserted and recovered from bony tails at four different praziquantel doses. The
number of tapeworms removed per fish is the number of tapeworms recovered during treatment plus the
number detected when the fish were dissected.

Mean (ranges) Mean (range) Total Total % of tapeworms
Dosage number of tapeworms number of tapeworms tapeworms tapeworms established
(mg/mL) inserted per fish removed per fish inserted recovered in bony tails
0.7 3.0 (1-8) 1.2 (0--6) 74 30 40.5
1.5 5.6 (2-13) 2.0 (0-15) 146 51 34.9
6.0 7.6 (3-23) 5.5 (0-39) 210 133 63.3
6.0 (adult) 13.2 (2-30) 0.25 (0-1) 93 2 2.2
36.0 2.7 (I-{)) 1.0 (0-5) 72 27 37.5