Interesting read. Any thoughts on how a crawfish compares to fat head minnows as far as surviving in low oxygen environments?
FH have good low O2 tolerance. Craws have better low O2 tolerance.
Procambarid crawfish
are generally tolerant of low oxygen
levels, but persistent exposure to
extremely low oxygen concentrations
can reduce production. Juveniles are
most susceptible to chronically low
levels. When dissolved oxygen
remains consistently below 1 ppm
throughout the day for several
weeks, crawfish become sufficiently
stressed that they may stop feeding.
Levels consistently below 0.5 ppm
may affect molting and reduce crawfish
survival. Other important water
quality variables are pH, total hardness,
total alkalinity, iron, hydrogen
sulfide content, ammonia, nitrite and
salinity (salt content). Desirable values
are between 6.5 and 8.5 for pH,
more than 50 ppm as CaCO3 for
total hardness, more than 50 ppm as
CaCO3 for total alkalinity, less than
0.1 ppm for ferrous iron, less than
0.002 ppm for hydrogen sulfide, less
than 0.06 ppm for un-ionized ammonia,
less than 0.6 ppm for nitrite, and
less than 6 ppt for salinity.
Fatheads In OH lab study, females exposed to dissolved oxygen of 2.0 mg/l for 11 months produced fewer eggs, those exposed to dissolved oxygen 1.0 mg/l for 11 months did not spawn . In MO study, mean critical dissolved oxygen .73 mg/l . Tolerates low dissolved oxygen. An OH lab study found fry survival reduced at dissolved oxygen less than 4.0 mg/l, and growth reduced significantly at dissolved oxygen less than 7.0 mg/l . In an OH lab study, incubation was significantly increased at successively lower dissolved oxygen concentration .
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