Captive Propagation and Tadpole Husbandry
(continued)
rearing tub setup
dinner time!
tadpole with air blister
tads of various sizes
approaching metamorphosis
yesterday a frog, today a froglet
Tadpole Husbandry
For rearing tubs, I used plastic containers that are well seasoned - that
is, old enough that the catalysts, esters and other nasty chemicals used in
production have had a chance to out-gas. I set up five separate tubs,
with two containers having frog-tight lids (the popular Critter Keeper
brand). The lids were left off for now but those would come into play
later on as the froglets emerged. One end of the tubs was propped on a
one inch high wood slat, in order to provide a deep and a shallow end.
Water was added to a depth of two inches at the deep end, and a small plant
was added for cover and to provide a place for froglets when they emerged.
Pothos, the very common houseplant with heart-shaped leaves, is very
useful for this, since it will grow and root in water. A full spectrum
bulb in a reflector fixture was suspended over the tubs to emulate sunlight
and provide warmth.
When the tadpoles emerged from the nest, they still had very large yolk sacs, from which they draw sustenance. After several days in the rearing tubs, the yolk sacs had diminished to the point that it was time to provide food. I offered a mixture of Tetramin Tropical Fish Food, combined with Spirulina blue-green algae. I powdered the Tetramin flakes by rubbing them between finger and thumb, and mixed it with the Spirulina (I use the capsule form, available at health-food stores).
Most tadpoles are bottom feeders, and sprinkling food on the surface of the water can cause problems. The tadpoles will rise to the surface to eat the food, and often they gulp air in doing so. This can lead to 'air blisters', as pockets of air get trapped in the tadpole's body, usually a fatal condition. To avoid this, after sprinkling the food on the water, I used my trusty plastic watering can (the frog breeder's other favorite tool) to sprinkle the surface. This breaks the surface tension and the food is mixed throughout the water volume.
The tadpoles were fed twice a day, and the amounts were fairly small. This is more art than science - you want to offer enough food so that each tadpole feeds well for perhaps 10-15 minutes. Too much and the water is fouled; too little and the tadpoles won't grow. Fortunately P. leucomystax tadpoles do not eat each other.
Waste products were removed before each feeding, using the turkey baster. The process also removed around half of the water, which was then replenished with fresh water. I used tap water, which was dechlorinated and aged in a pair of five gallon buckets, each with an airstone to keep the water aerated. Once a week each container was emptied and thoroughly cleaned.
The tadpoles grew at a steady rate with few losses. After several weeks, it became apparent that some tadpoles grew faster than others. The tadpoles were then sorted by size in the five containers, with the larger ones going into the tubs that had lids. By the second week the hind limbs had emerged, and a week or so later the front limbs appeared. At this point lids were added to the tubs; the metamorphosis from tadpole to froglet was fairly quick, often in 24 hours or less. The froglets were left unmolested in the tubs for several days as they completely changed into frogs; this was another delicate point in the cycle and stress was to be avoided.
A small portion of tadpoles, perhaps five per cent, never morphed into frogs. They grew to a certain size, and development stopped. Eventually they became somewhat spindly in appearance and withered away. Since the number of affected tadpoles was small, my guess is this may be a natural occurrence.