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Tolerance of Channel Catfish Fry to Abrupt pH Changes
Author(s) -
Mischke Charles C.,
Wise David J.
Publication year - 2008
Publication title -
north american journal of aquaculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 41
eISSN - 1548-8454
pISSN - 1522-2055
DOI - 10.1577/a07-047.1
Subject(s) - catfish , ictalurus , stocking , hatchery , biology , fishery , zoology , human fertilization , morning , fish <actinopterygii> , agronomy , botany
Fry survival in the catfish industry is variable, and failure to survive cannot be completely attributable to diseases, fertilization practices, or lack of zooplankton abundance. The variability in fry survival may be related to current handling and stocking methods. When stocked, fry are transferred relatively quickly from hatchery water to pond water. Generally, temperature differences are monitored between hatchery water and pond water, but little attention is paid to pH differences. We conducted studies to determine the tolerance of channel catfish Ictalurus punctatus fry to pH changes. Catfish fry showed a high tolerance for decreasing pH values but a relatively low tolerance for increasing pH values. We estimate that an increase in pH of 0.7 units will cause 10% mortality in 8‐d‐posthatch catfish fry, and an increase of 1.4 pH units will cause 50% mortality. We recommend that farmers monitor pH before stocking fry and stock ponds that tend to increase in pH throughout the day early in the morning.