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Control of an Infestation of a Fish Leech ( Myzobdella lugubris ) on Catfishes in Tanks and Earthen Ponds
Author(s) -
Morrison John R.,
Fox Steven R.,
Rogers Wilmer A.
Publication year - 1993
Publication title -
journal of aquatic animal health
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 52
eISSN - 1548-8667
pISSN - 0899-7659
DOI - 10.1577/1548-8667(1993)005<0110:coaioa>2.3.co;2
Subject(s) - leech , catfish , ictalurus , biology , brood , infestation , fishery , fish <actinopterygii> , toxicology , zoology , larva , veterinary medicine , ecology , botany , world wide web , computer science , medicine
An infestation of a fish leech, Myzobdella lugubris , was discovered in a brood pond containing female channel catfish Ictalurus punctatus and mixed‐sex blue catfish I. furcatus . Three chemical treatments ‐trichlorfon (0.5 mg/L), formalin (150 mg/L), and sodium chloride (1%)‐were compared for their effectiveness in the control of this parasite on individual fish held in tanks at 21–23°C. Trichlorfon demonstrated the greatest leech reduction (34.4%), followed in effectiveness by formalin (28.9%) and salt (17.2%). In further experiments at 26–28°C, 0.5 mg trichlorfon/L achieved 91% reduction of attached leeches in 6‐h tank treatments and 100% reduction after 48 h in small ponds. Two applications of 0.5 mg trichlorfon/L 21 d apart were required for complete leech elimination in the brood‐fish pond. The initial application resulted in 100% reduction of attached leeches on fish sampled 8 d afterward. Reinfestation occurred between 8 and 21 d after treatment, as indicated by the presence of small leeches (5–12 mm in length). After the second application, no leeches were observed on any of five subsequent sample dates over the remainder of the 11‐week study period. Trichlorfon seems to be effective in the control of M. lugubris on brood channel and blue catfish when this chemical is used as an indefinite treatment at water temperatures above 26°C. Repeat applications will probably be required in ponds with reproducing leeches.