IMHO - when in doubt supplement with B1 3-4 times a week. If feeding fresh/frozen, pre-soak in an aquatic based vitamin/mineral supplement that is known to contain B1. If feeding live, gut load the live feed immediately prior to feeding your fish. Or feed pellets a few times a week.
Black cod does have thiaminase but haddock is ok.
I was referring to Atlantic Cod, which doesn't have thiaminase, but good point which highlights what it says on the site RD referred to:
"Take note that whether or not a fish contains thiaminase can differ even amongst different species of the same type or family of fish: for example, Pacific mackerel does contain thiaminase while Atlantic mackerel does not."
No.Does clarias catfish have thiaminase?
Yes.North American catfishes do contain thiaminase though right?