species that stays small, and it is quite non-aggressive, especially for a cichlid. You might
look through some pictures of fish species or
send us a photo of the fish. Judging by its
behavior, it sure sounds like a Dempsey.
It is possible that the oscars are a pair and
simply not good parents. But it was a smart
move that paid off to put the second fish in,
as oscars, normally easy targets, can be quite
formidable as pairs.
Regarding plants, they provide refuge for
fish and help in that respect, and they also
help remove nitrates from the dissolved water.
But with all the big fish that you have, you
will be doing a lot of partial water changes
anyway. So you may be better off with
artificial plants. If you are determined to have
natural plants, I would advise Vallisneria as
the ones most likely to survive, but even they
may not. As you already know, your tank is
very overcrowded. That 250 will certainly
I have had a 60-gallon
freshwater tank for 12 years
with no problems. Now I’m dealing with
this blue-green slime on everything. I
tried to keep the lights out, but that
only had a short-term impact. Then I
tried to use erythromycin, while still
keeping the lights out. That seemed to
work, but only for about six months.
Now it’s back.
The water seems okay. I’m adding plant
supplements, nitrogen, phosphorus, and
potassium. I have about 30 small fish,
which I feed once a day. I have a power
filter, and I added two air stones for
circulation. The temperature is around
78°F. I do a 20-percent water change
every two weeks. I have lots of plants and
a couple big rocks with three pieces of
bog wood. Green slime has grown mainly
on the gravel, rocks, and plants. I have
regular green algae on the glass with lots
of tiny bubbles. Any suggestions would be
It seems counterintuitive,
but I would suggest that
you increase your lighting
time. Vascular plants should
be able to out-compete blue-green algae
(cyanobacteria). Try extending your lighting
time and maybe even increasing the number
A blue crayfish Procambarus clarkii.
The pugnacious Jack Dempsey Archocentrus octofasciatus, a wild-caught specimen from Belize.
of vascular plants in the tank, such as but can dwarf cichlids, such as apistos and
floating water sprite. The idea here is that kribensis, be mixed without problems?
the true plants will eventually starve off James Turner
most of the blue-green algae. Increasing the Meridian, Mississippi
volume and frequency of your water changes
should also help. Some of the purists like to have
the tanks look as natural as
possible, so there is something
of a snob factor at work here.
I know that some cichlid It’s like the way some of us are disdainful
hobbyists don’t like the idea of a burping clam shell or a bubbling diver
of mixing cichlids from different localities, decoration in an aquarium (even though