by David Snell
I purchased a pair of Head-and-Tail Light tetras from the Centreville Aquarium shop in late October 2000. I put them into my tetra conditioning tanks. As with other Hemigrammus species, it’s fairly easy to distinguish the males from the females. The males are more slender than the females, while the females appear to be more full and round in the midsection. Also, when viewing the females head-on, the females that are filling up with eggs appear visibly wide.
The conditioning tanks had a pH of 6 to 6.3 and a conductivity of 380ms. The tetras were fed mainly frozen bloodworms, live blackworms, newly hatched brine shrimp, and live fruit flies. In a few weeks’ time, the female was very noticeably filling with eggs.
For my spawning tank, I had set up a 5.5 gallon tank that was filled with about 3 gallons of RO water, with a conductivity of 50ms, and a pH of 6.3. The water temp was about 78-80°F. The water was treated with a double dosage of Kent Blackwater Extract. I attached a small piece of Java moss to a small lettuce clip that was attached with a suctioned-cup to the back glass panel. On the bottom of the tank was my homemade spawning grate that would allow the eggs to fall to the bottom of the tank and be separated from the adults above. Since tetra eggs can be light sensitive, the tank was covered with a dark towel to reduce the amount of light.
The pair was placed into the spawning tank on November 19th. Two days later in the morning, the pair had spawned. I noticed there were about 300-400 eggs. It looked like about 10% of the eggs had already fungused. The adults were immediately returned to their conditioning tanks. I was concerned that more eggs would fungus during the course of the day so I left the towel covering the tank.
Within 24 hours, the eggs started to hatch and I could see wigglers on the bottom of the tank. The fry only looked a few millimeters long and they looked like small slivers of glass. With in 36 hours it appeared that all the viable eggs had hatched. There were 300 or so fry on the bottom of the tank. By the second day, I added 1/2 cup of water from my paramecium culture to make food available to the fry when they became free swimming. As with the Hemigrammus erythrozonus fry, I found the H. ocellifer "hanging" on the glass nearly motionless.
On the third day, I added another 1/2 cup of paramecium to the spawning tank. By the 5th day, all the fry were free swimming. The number of paramecium visible in the tank had declined. On the 6th day, I decided to try and start feeding the fry newly hatched brine shrimp. Although the fry appeared to be too small to consume newly hatched brine shrimp, the fry were able to eat it with out much problem. At this point, I discontinued feeding paramecium and continued the newly hatched brine shrimp.
I started doing water changes about once a week with more RO water. The Head-and-Tail Light tetras seem to grow more slowly when compared to the growth of the Glowlight tetras. The 5.5gallon tank was not likely the ideal size tank for raising them.
Over the course of the next two months it was clear that the number of fry were declining, but the strong remained. At about 6-7 weeks, the color of the fry started to look like the adults with the noticeable "head and tail" light. At about 2.5 months, I had about 80-100 remaining tetras. I moved about half the tetras to my 75 gallon planted tank, and I auctioned off the other half in 4 bags at the PVAS 2001 Winter auction.
This article first appeared in PVAS’s Delta Tale, Vol 32, # 3