About three years ago I purchased half a dozen Corydoras adolfoi at an auction in Orillia. One of the local hobbyists in the area had been raising them in quite large numbers – one of the few people I’ve heard of being able to do that. The corys went home with me and ended up in a ten gallon tank with a few tetras of one kind or another. Somehow I never got around to seriously trying to breed them and by this time a year ago I still had five of them but they all had a male “look” to them.
I had decided to keep an eye open for some females and on a visit to The Fish Place in North Tonawanda (one of our Bulletin advertisers) I saw what I thought was just what I wanted – a tank of corys labelled “adolfoi” that were larger and fatter than mine. A bit expensive, especially with the high US dollar, but three of them went home with me.
I’m sure you’re all ahead of me and realize that once I had the fish home and settled in, I realized they were not Corydoras adolfoi, although at that time I didn’t know what they were.
Aside from being a little larger than the adolfoi, they also had a somewhat darker body – the adolfoi seem brighter. But the most obvious difference was the black stripe on the back; it was much wider and maintained its width whereas on the adolfoi it narrows, almost to a point, at the caudal fin. A bit of searching, mostly on the Internet, lead me to the fact the fish were actually Corydoras duplicareus (Sands, 1995).
According to most sources I’ve seen they are found in conjunction with a few other, similarly patterned corys – adolfoi, serratus, and imitator. They originate in certain tributaries of the Upper Rio Negro in Brazil. One source, “Aqualog, All Corydoras”, is specific in listing their place of origin as the Rio Poranga.
Although I haven’t kept them, Corydoras serratus is supposed to differ in being a ‘long nose’ cory and has serrated pectoral spines. C. imitator is the ‘long nose’ companion to adolfoi and has a black dorsal band that narrows towards the tail.
My three fish came home with me from the States and ended up sharing a ten gallon tank with half a dozen Rasbora hetamorpha. Because of the Rasboras, I was keeping the water fairly soft and water changes were usually done with 50/50 tap and RO water. Conditions seemed to suit them there and four or five months went by. Then one day, out of the blue, one died and I was left with two fish that, in all honesty, I wasn’t certain I could sex. But at least neither of those two died and before I knew it, Fall arrived.
Whether it’s true or not, it has always seemed to me that corys, wild ones in particular, are much more willing to spawn from early fall to mid spring than they are at other times of the year. And so I finally got around to setting up the duplicareus and trying to get some eggs.
I used a simple arrangement that has worked well for me in the past with a number of different Corydoras species. The two fish were put in a five gallon tank with about an inch of sand on the bottom. Filtration was a standard sponge filter and there were no plants in the tank since the lighting was not very intense. The original water was from their old tank and each day I did a change of about a quart, using RO water, until I felt the softness was appropriate (about a week).
About mid November I looked into the tank to see one of the fish (a female obviously) with a single egg held in her pelvic fins. By the next day there was no sign of that egg or any others but it would appear that at least I had a pair! Since it didn’t seem that this species wanted to stick eggs all over the glass (like C. aeneus for example), I added a floating spawning mop that was long enough to touch the sand.
My experience has been that there are two things (among others) that help to ‘trigger’ corys to spawn. One is water changes with cold water and the other is a change in the barometric pressure. I hadn’t added any cold water to the tank but near the end of the month we did have a number of high and low pressure systems move through our area. And sure enough, as I went to feed the fish, the duplicareus were chasing each other in a typical Corydoras pre-spawning frenzy. I suppose, actually, the male was chasing the female. The next day there were no eggs on the glass but when I checked the mop I found sixteen – not a lot but at least a start. One of the spawning reports I read stated that these fish lay their eggs almost entirely on or near the substrate. I found more than half the eggs at the surface near the float and the rest very close to the sand. Who knows? Maybe different pairs have different preferences.
As is my habit for mop spawning corys, I picked the eggs and put them in a small container with a little methylene blue. I decided to use tap water in order to make water changes a little simpler. The eggs were large, fairly sticky and somewhat whitish. An inexperienced breeder might have thought they were already fungused. But over the next few days, developing fry could be seen in the eggs and on day six, twelve of the sixteen eggs hatched. The newly hatched fry are large – about a quarter of an inch – and have an egg sac which, it turned out, took the best part of five more days to be absorbed.
The fry were placed in a three gallon tank with only two or three inches of water; over the next few days the tank was filled, an inch or two a day, until it was full. After that I tried to change a pint or so of water each day.
The fry seemed to do quite well and ate microworms and live baby brine shrimp; they grew noticeably within the first week or ten days. I also put some newly hatched killies in with them since the tank could support a few more fish. Everything worked well with the corys on the bottom and the killie fry mostly at the surface.
At the time of writing, the fry are about four weeks old and seem to be growing well. Only one has died. They do not yet have the adult pattern but the typical spotted baby pattern is slowly changing and I imagine that within another month (all going well) I’ll have a dozen duplicates of my duplicareus.
Author: Paul McFarlane; Hamilton and District Aquarium Society
Source: Aquarticles (no longer available)
