Protocol for breeding Hymenochirus boettgeri in captivity

Abstract

Hymenochirus boettgeri is a sexually dimorphic species, with females ty pically exhibiting a larger oval-shaped body (up to 35 mm in snout-vent length (SVL)), while males possess a large obiculated tympanum and a lateral post-axillary subdermal gland that increases in size and vascularity during sexual activity (Figure 1).

Figure 1. H. boettgeri female (superior) and male (inferior) adult individuals. Black arrow points to post-axillary subdermal gland and black bar represent 1 cm scale.

Steps

Sexual selection

Select male H. boettgeri specimens with heavily vascularized glands and the largest females for breeding.

Note

Sexual maturity will depend on the conditions in which the animals were raised (e.g., space, diet, temperature). Observing the glands in males and an increased body size in females will indicate that they are sexually mature. In our systems, the male glands were first observed at 5 months of age, and females spawned for the first time at a minimum of 6 months of age.

Keep males and females in separate 38 L glass tanks by sex at 25°C with conditioned water as described in the “Housing and Care for Hymenochirus boettgeri” protocol and 13:11 light-dark cycle.

Feeding

Feed the frogs ad libitum twice per day for ten consecutive days, providing newly hatched brine shrimp as the first meal of the day, and offer either frozen gamma-irradiated bloodworms, live blackworms, or small-granule fish food as the second meal of the day, changing the combination daily if possible.

Pair selection

After 10 days of enhanced feeding, choose breeding pairs consisting of one male and one female each.

Mating tanks

Using an aquarium net, place each breeding pair in separate 8 L plastic tanks at 21 °C, with a minimum water volume of 2 L per individual.

Note

These tanks should not have any enrichment, filters, or heaters to facilitate egg visualization and collection.

Allow the breeding pairs to remain together for one to four days, during which mating behavior is expected.

Observe the frogs closely during this period. If the pair does not reproduce, consider replacing one of them with another animal to create a new pair combination.

Egg Collection and maintenance

After mating, collect the eggs as they are laid using a sterile siphon or spoon and transfer them to net breeder tanks as described in “Housing and Care for Hymenochirus boettgeri” protocol.

Check the eggs daily and remove any that contain fungi growing or that haven't hatched after 4 days of being laid.

Water safety

10.

During the breeding period, feed the animals and, if necessary, perform a water change as described in the “Housing and Care for Hymenochirus boettgeri” protocol.