by Dennis Rawlinson, uploaded January 01, 2002
Shane's Note: Below is a short article about Dennis' first spawning of Dianema urostriatum. Although no fry resulted from the spawning, I believe it is important to get the information out to the community.
This species has been spawned before but I am unaware of any written reports in the English language aquarium literature. The most difficult aspect with this species seems to be actually getting them to spawn. The fry should not prove too difficult to rear as long as the rearing tanks are kept uncrowded, clean, and heavily fed on quality foods.
I am currently maintaining two variations of D. urostriatum. One group has one a longer caudal-fin than the other and the caudal-fin appears to ascend further up the caudal peduncle. I am unsure if this is normal intraspecific variation between two different localities or within a single population. The short-tailed variety bred for me on 20 February 2000. Unfortunately, they ate the eggs before they were removed. No nest was observed and the at the time of the spawning. The eggs, which were white, were laid 2- 3 deep in a circular formation approximately 1-1/4" in diameter. I witnessed the fish spawning in the afternoon and the description of the "nest" is from that time. The eggs were deposited while the fish were upside-down and swimming side by side. The parents would then leave for a few minutes and repeat the spawning run at intervals of about 10 minutes.
Occasionally, the male would return to the nest and travel across its length inverted. I assume he was again trying to fertilize the eggs. The eggs were deposited under a floating plastic cover about 4" in diameter. There are two pairs of D. urostriatum in the tank which holds approximately 10 gallons. It measures 16"x23"x10" and contained between 4-5 inches of water. The pH was 6.2, hardness less than 2GH, and ammonia less than 1.0. There was no filtration or aeration at the time of the spawning as I had shut them off four days before. At the same time I had lowered the depth from 8 inches and removed the filter. Temperature was variable from 68-72F with the cooler end at night. The fish were fed heavily on blackworms and frozen blood worms.
As there are two pair in the same tank, I am unsure which two are doing what. This could be a problem since it is likely that the non-spawning fish are eating the eggs. I'm going to start the fish on the same cycle that I maintained before the last spawn and cross my fingers. Only the next time, I will collect the eggs earlier!