Corydoras semiaquilus by Eric Bodrock
Corydoras semiaquilus "Yaranayuto" (12-30-00) -- I received these fish from a friend, Julio Melgar, who collected them in the mid part of 1999 while on a collecting trip in S. America. Julio brought back C. semiaquilus from four different locations from the trip. My group of seven from Yaranayuto acclimated rather well. When I first received them I quarantined them in a tank of their own. As with all new wild fish I receive, I quarantine them before they go into any of my main systems to avoid introduction of any diseases. After about an eight-week period, they were added to a fifteen-gallon tank on system "B". During quarantine I noticed that the fish are a bit aggressive towards one another. I added plenty of cover in the form of plants, a few rocks and some sunken mops and made sure they were well fed. While in quarantine I lost two of the fish and would guess from fighting! I want to mention that at the same time I got the fish from the Yaranayuto location I also got a group from the Momoncillo location. These fish were very aggressive. They were always chasing one another about the tank, not as in a spawning behavior. I would watch them line each other up and take a swimming run from eight inches away and ram into the side of another! Wouldn't believe it if I didn't see it for myself! After several months I was down to one of the Momoncillo and she was added to a thirty-gallon breeder tank with some other adult Corydoras species and reacted the same way with them! After a year by herself, she has settled down and is peacefully coexisting with some other adult Corys. The Yaranayuto aren't as bad as them but noticeably aggressive. Provide plenty of cover for hiding.
I would guess that after about
3 months after being added into the system I noticed just a few eggs and
some marks where eggs had been deposited on the tank sides. Their eggs
are good size, 1.5mm or so. They were all white in color (not good) and
none hatched. A month later I noticed a larger spawn of nearly sixty
eggs. Only three fry were raised from that spawn and I eventually lost
those, but luckily some photos were taken. For almost six months no
further signs of spawning was noticed. I then moved them from system
"B" into system "A". Thinking that a little larger tank with
more room and different water may trigger them to spawn. Nothing
happened. This past November I received the last handful of Yaranayuto
that Julio had. Knowing that Julio had them for over a year I added them
straight in with my group. That seemed to get them all very active.
Within several weeks I seen a few eggs scattered about on the aquarium
sides. None of those eggs were any good. The aquarium they were housed
in was on the top row of the system. I had a large spawn of Corys in the
tank under them were I had moved the parents and left the eggs in the
tank for hatching. For that reason, the Yaranayuto's had to be shut
off of the system to stop their water from overflowing into the bottom
row, (see system "A"). Leaving them with just a sponge filter, I did
a 75% water change a week later. Several mornings after the water change
I spotted a few eggs in the tank and watched as the breeding group
continued to spawn. The Temp was at 74F, pH around 6.8. My TDS meter
read 205. The female carried a single egg in her pelvic fin. A slight,
quick spawning "T" position between a male and a female was noticed
periodically in the activity. Males would occasionally chase her, with
the appearance of nibbling around her head and sides. All the fish get
very active during the spawn. The female looks as to be cleaning
surfaces to lay eggs on, but I never seen her lay on a smooth surface.
She would deposit some eggs on the very tip of plant leaves, signally.
Or, she would be seen forcefully driving into plant roots or a yarn mop
and to deposit her eggs. Even in a mop it is rare to find any two eggs
close to one another. Spawning can/did take place for a couple of days.
A problem with all of the activity is that they WILL eat eggs if they
come across them. Again, make sure there is a bunch of cover! Mops with
eggs are moved into a smaller tank or shoebox, kept dark, and aerated
for hatching. Any eggs found on plant leaves are picked and put into the
mop for hatching. Hatch rate is very low, under 20%. Rate of growth is
quick. Adult males reach a total length up to 7cm while the females get
a bit larger up to 8cm. Females have a slightly thicker body but not as
noticeable as many Corydoras are. Also, the females don't get very
heavy before they spawn. You have to check the tank, plants and mops for
eggs regularly or you may never know they spawned.