Re: NANFA-- swimming upstream?

R. W. Wolff (
Tue, 17 Dec 2002 00:20:32 -0600

Not sure what is wrong with your fish, but I keep one genus of fish that is
notorious for finding its way out the smallest hole in the lid. Rivulus.
Often they seem content for even months, to suddenly find them laying on the
floor. Luckily they are hardy and need to be dried crisp to die. Now that
you mention it, my jumpers seem to go in waves. Always a misplaced lid that
lets them out, since keeping these fish I usually have my tanks nearly
sealed. Putting some of the craft needle point cloth ( plastic with square
holes) cut to the shape of the filter out flow can block this area, and
still let water pass through. I have also taped over the entire thing with
clear packing tape, but fish will then get up in the filter, and it seems
they some how get chewed up in the impeller, since I do not use filter pads
in my power filters. I would guess that since in my case it is several
tanks, that water change may simulate a spring time flood, and the fish
decide to move up stream. Luckily with the still water fish a layer of some
kind of floating plants often stops any from leaving the tank, only to have
them lay on top of the plants, since this is normal behavior for many
rivulus. A fascinating fish, and many are North American species, by the

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