Those who breed annual fish encounter enough natural problems, but there are a few misconceptions that can make their task even more difficult.
“In keeping South American annuals … I have run into plenty of bad information,” says Darrell Rommie. “By experimentation I have determined where [some of] the problems lie.” He offers the following observations.
Dry the spawning peat out overnight between two newspapers. Drying out peat overnight between two layers of newspapers usually dries the peat out too much; the eggs will desiccate and die.
Seal in a plastic bag and store at room temperature. Coupled with too-dry peat, incubation of annual eggs at room temperatures (70-75F) prolongs the incubation time and allows the peat to desiccate even more, resulting in poor or nonexistent hatches.
To hatch out the eggs, dump the peat into some tank water an inch deep. Tank water contains potentially destructive bacteria and is usually also deficient in oxygen. Water one inch deep water only ensures that small water changes will be totally ineffective in reducing the effects of decaying uneaten food.
So what does Darrell now do to better his chances of success with annual fish?
He uses covered spawning containers, with boiled sphagnum peat moss as a substrate. Every week or so he removes the peat, squeezes it gently in a net, spreads it out over a layer of damp paper towels and scans carefully for eggs. After he fluffs the peat with his fingers he stores it in a plastic bag properly marked with the species name, the date, and the notation “eggs seen.” Incubation is at 80F. Darrell checks the bags in storage weekly for adequate moisture, refluffs the peat and reseals them.
After about five weeks he places in the peat in a three gallon container and pours in cold (higher in oxygen) water to the halfway mark, 5-6″ deep. The fry hatch out overnight and are fed Wardley’s Liquifry-Egglayers and newly hatched brine shrimp nauplii.
“Obviously, at the speeded up times, not all the eggs will hatch,” he says. “This is where some advice from the past comes in real handy – ‘siphon off the fry and rinse and squeeze and rebag the peat for another 4-6 weeks and then try again.’ “
Reference: Romaine, Darnel. “Too Dry, Too Long, Too Bad!” AquaTropica, volume 2 Number 1. (http://biodec.wust1.edu/~hrbek/aquatrR211.html)
G.C.K.A. Newsletter, July 1998