Biotoecus opercularis …A challenge?
by Rich Grenfell
From Wet Pet Gazette, Norwalk Aquarium Society
Aquarticles
Introduction
These interesting little fellows come to us from northern Brazil; they inhabit
blackwater sections and have been caught mainly around the town of Barcelos, in the Rio
Urbaxi, and Rio Branco.
Description
Mature males are about 2 inches TL, females are slightly less. The body is elongate,
and when not in breeding dress, the coloration is a drab olive green across the back, and
silverish on the flanks. The belly region is white. They have five dorsal blotches
beginning at the base of the dorsal fin, and heading back to the caudal peduncle. They
also have another six of these spots mid-body. Mature males will have very obvious
extensions on the tip of the dorsal, and both corners of the caudal fin. The female will
have rounded fins with a much plumper abdomen. When breeding, they will take on a
beautiful light green color over most of the body. The males will have a dazzling display
of pastel coloration in the fins, and the females' ventral fins take on a dark
yellow/orange color.
Care
These fish became available to me at the NEC Convention 2001. They were quite expensive
at that time, and a friend and I pooled our money and ended up with 10 young fish. We were
advised that they were going to need special care, such as RO (reverse osmosis) water, and
live foods only. Since my friend had RO and I didn't, the little guys went home with him.
After a few weeks of RO water changes and nothing but live blackworms and brine shrimp, he
decided to toss in a bit of homemade paste food, and see what they would do with it. To
his surprise they attacked it, eating up every scrap! Since we were told that this would
not happen, he decided to see how they would do without the RO water. They spawned within
a few days! Since caring for these fish turned out to be quite different than we were
advised, I took my group home.
Environment
They were set up in a 10-gallon tank, with a half-inch of black sand on the bottom. The
plants consisted of an Anubias in the center, with some Java fern in the corners. A large
piece of driftwood covered with Java moss laid across the back of the tank, and some water
sprite was sprinkled across the top. This fish needs very small caves. I took some
flowerpots and broke them into small pieces and placed them about the tank to provide
spawning places for them. A sponge filter in one corner supplied filtration.
Water
Good old New Haven CT tap water! I had success with discus on my tap water, so I didn't
see any reason why the bios wouldn't do just as well. The pH fluctuated between 6.6 and
7.0, with a GH of just 4 degrees. Temperature was set at a steady 83 degrees, and water
changes of 30% were done weekly. Food As with any other fish that I am attempting to
breed, I provided them with a varied diet high in protein. They were fed twice daily with
a rotating menu of frozen and live brine, frozen bloodworms, live blackworms, frozen
daphnia, and a good paste food. Given this and the frequent water changes, it wasn't long
before they were in breeding condition.
Breeding behavior
The fish turned out to be quite the little excavators! The female picks out a nice
little cave from the flowerpot shards provided, and begins to dig, until there is a nice
lip of sand built up outside the mouth of the cave. She spends quite a bit of time doing
this and this is a good sign that a spawning will soon take place. The male makes sure
that all other fish stay out of the area. They spawn much like apistos, with the eggs
being attached to the ceiling of the cave. The eggs hatch in three days or so, and the
young are kept on the inside the cave until free swimming. They are free swimming in 4 to
5 days, and are then herded around the tank by mom. She is very careful to keep any
drifters within the group. The male fish defends the fry for the first day or two but the
fry care is undertaken mainly by mom.
Raising the fry
I wanted another spawn, so I removed the first spawn after the first week, and placed
them in their own 20 long. This tank was bare bottom, with a few water sprite floating on
top. They aren't large enough to take BBS right away, and I used microworms, and some
powder food for the first 3 days. I then fed them 3 times daily with BBS. They grow
surprisingly fast at first, but growth slows considerably after a few weeks. Mine were
just less than 1 inch at approximately 4 months old.
Conclusion
Despite what I was told about these fish, I found them to be quite hardy, and easy to
work with. I enjoyed them completely and ended up with more fry than expected. Their small
size lends to easy space requirements, and they are quite eclectic in their food
preferences. If you are looking for a bit of a different dwarf, give bios a try, they
won't let you down!
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