Can mating be deadly?
Although it has not ever happened to my frogs I have seen a few instances in which a frog has died while mating or associated with mating.
First let me say this is rare. It is extremely unlikely to happen. Let’s consider some of the reasons it could happen and how we can mitigate the risk.
Males develop territories while mating. If another male enters the territory and sings he will be confronted with a defense stance and zigzagging forward and backward to frighten him away. This may result in fighting but is more likely to result in the intruder leaving. The more male frogs there are in a small space the more likely fighting will occur. They both will take the defensive posture, push against one another and sometimes one will pin the other down. This is unlikely to result in drowning considering that both have to surface to breathe but it can happen.
If a male enters the space without singing he may be embraced by the breeding male. The embraced male will stretch out his legs into a crossed position and the breeding male should release him. An unripe female will do the same when embraced.
When a ripe female enters his territory he will embrace her. They may be in this position for several hours before they begin to lay eggs. This is normal and a healthy adult female should be just fine in this situation. Egg laying can last for many hours. When she is finished she will stretch her legs out and the male should release her.
What can go wrong? If a frog is sick, weak, or too small they may not be able to handle being embraced (as a mate or a rival). If the male is a particularly aggressive breeder the embraced frog may not be able to convince him to let go. If the frog does let go and the embraced frog cannot hide it may be embraced again. If the water is too deep the female can become exhausted.
How can we mitigate this? To begin with keep young frogs separated from the adults until they are at least 3/4 of the adults’ size. This is a general recommendation and I encourage you to use your own best judgment. You may want to wait until they are fully grown. If you suspect that a frog is sick or wounded separate the frog for medical treatment. This could be done with a tank divider, breeder box, or a separate cycled aquarium. With very small colonies it can help to have more females than males but we usually don’t get to choose. The ratio becomes less of a problem as the size of the colony increases.
Aside from small or sick frogs, and regardless of the ratio of male to female, creating a more natural environment for them can help reduce the risk. Keep water depth to 12” or lower from substrate to surface. If you think the female is struggling lowering the water level may be enough to protect her. Keep a larger colony to distribute mating behaviors. Provide lots of places to hide. And offer places to hang out near the surface for the female to rest and breathe while in amplexus.
We can also try to discourage breeding behavior. These animals live in the tropics. Their days consist of 12 hours of daylight throughout the year with very little seasonal difference. They experience two seasons, the rainy season and the dry season which still has rain just less of it. Drought/flood conditions in the wild stimulate breeding. We create these conditions in our aquariums once a week with water changes. In the event that we want to discourage breeding behavior we can pause water changes. Most people perform weekly water changes. Try stretching it out for a second week by performing much smaller, more frequent changes. Maybe one large plastic cupful of water daily. This will also dilute sex pheromones in the water column. There are gravel vacuums that can allow us to remove waste without removing water. You could consider using one of these for cleaning the tank without removing too much water and simulating drought/flood conditions. When they experience flooding the temperature drops. When we replace the water during water changes matching the temperature will help to avoid simulating flood conditions and could reduce mating behaviors. ***Please understand that I am not at all suggesting avoiding water changes. I’m saying that if you need to reduce breeding behavior perform smaller water changes more frequently with water that matches in temperature and use a tool to clean out detritus that won’t also remove water.***
Last, and certainly not least: