Letters to the Editor
Hard to Believe
I’m kind of new to the hobby (three
years) and have a planted 75-gallon
aquarium with 4 discus, 40 to 45 neons/
cardinals, 10 black neons, 10 zebra
danios, a black-and-white pleco, a sailfin
pleco, and 6 glass ghost cats (Kryptopterus
bicirrhis). I’ve been told that these won’t
live together, but they all seem to be very
happy and have been together now for
around eight months. My water quality
is great, and I do weekly changes of
about 40 to 45 percent.
My question is about a couple of my
ghost cats. They have been doing this
very mesmerizing, almost dance-like
shimmy. They point their heads straight
up until they are completely vertical
and start shimmying, while bright neon
colors (blue, green, red) shoot through
their bodies. All the other fish take
notice, as do I! Is this a defense thing,
or another normal behavior of the fish?
Jason MacNeil
Alberta, Canada
My first inclination was to dismiss your
email as a prank. On the off chance
that I had simply never heard of such a
spectacular behavior in a popular species, I
checked with our resident catfish guru, Lee
Finley, who could offer only that perhaps
specimens injected with neon dye were
involved, and that the vertical posture and
shimmying—both indications of serious
health problems—could be due to that
abuse. While there are some fish known
to rapidly flash bright colors on and off,
none are in the genus Kryptopterus, a
genus notable in fact for its virtual lack
of chromatophores (pigment-containing
structures). Nevertheless, science often
progresses through examination of the
unexpected, so in the event that you
are being serious, my suggestion to you
would be the same as to anyone witnessing
an outlandish event: make detailed
observations and document your report—
in this case, with video footage.
Cycling in Reverse
I was wondering if reducing the stock
in my tank has to be done slowly, as
when adding fish to a newly cycled
tank. I have a 125 gallon that I started
last March, with two buttikoferi and a
pleco. These fish were in my 55 gallon
originally, so I used the gravel and
power filter from it, and that gave it a
good start. Slowly I added more fish:
a gold saum, a jag, and a dempsey. To
say they don’t get along would be an
understatement—I want to find homes
for all but the male buttikoferi. Will this
cause any ill effects to the biological
filter if done all at once? I have two large
biofilters, and water changes are weekly,
at 30 to 50 percent (whatever it takes to
get the gravel clean).
James Biesiada
Toledo, Ohio
When you remove fish from a mature
tank, the biological filter will die off relative
to the reduction in ammonia production.
Provided you do not wait and then add a
bunch of new fish, you will be fine. If you
remove fish and add more right away, that
will work, since the biofilter will be getting
the same amount of ammonia. If you just
remove fish, that will also work, since you
won’t need the part of the biofilter that dies
off. The only problem is if you remove fish,
wait a while—during which the biofilter
dies back—and then add more fish all at
once, since there will not be an adequate
biofilter for the increased ammonia.
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