Where are the eggs?

[Geoff]

In my experience it's quite common for Xenopus to produce eggs when they first reach sexual maturity. Whether they continue to do so in subsequent years is dependent partly on diet but mainly on environmental conditions. If the frogs are kept under constant conditions of photoperiod (light) and temperature all year round it's unlikely that they'll breed. This is because they originate from regions with a Mediterranean climate (i.e.:with slight seasonal variations) rather than tropical. The simplest way to replicate those natural variations (in the UK anyway) is to keep the frogs in an unlit and unheated tank so that the frogs experience ambient light and temperature. Under those conditions they're more likely to produce eggs in spring and summer.

[mpmistr]

Interesting, I keep my frogs at 72F in summer and 68F in winter, I guess it has something to with the photoperiod then. My tank has a lot of plants so I keep my lights on about 10 hours a day.

So I suppose if I wanted to ever breed these frogs I would need a separate tank kept around 68F and unlit for an extended period of time for them to reproduce?

I really thought I'd have some eggs at this point really. My male frog was raised alone in a 10 gallon tank for about 8 months, he was always calling for a mate. I finally added him to my tank with 3 adult females, he did perform amplexus constantly at first, but has cooled off now. I haven't seen it happen for quite some time, he does not sing any more either. Weird.

[Geoff]

I'll explain in more detail why I've concluded what I wrote above.

I had two pairs of young frogs which, on reaching sexual maturity after approximately a year, produced eggs. For the next 7 years they remained healthy and went into amplexus but there were no more eggs. During those 7 years I kept them in a lavishly planted natural-looking tank which, although pleasing on the eye, did not provide any significant changes in environmental conditions in terms of lighting (10 hours a day - controlled by a time switch) or water temperature, which, like yours, was roughly in the 68°F to 70°F range. Their tank was in a north-facing room and never received any direct sunlight.

Eventually, I decided to move things around and transferred the frogs to another tank, which was sparsely furnished with plastic plants, no substrate or artificial lighting, a few short pieces of upturned plastic guttering to provide shelter, a basic air-powered box filter and a sliding glass lid. This tank was situated in a south-facing room, which received direct sunlight (when it was sunny) for a large part of the day, although the tank itself did not. However, the room had a fluctuating temperature range. In winter, there was no heating on in the daytime when I was at work. In summer it got fairly hot (most homes in the UK don't have AC), which meant that the tank's water temperature gradually fell and rose accordingly from the low 60°sF to the upper 70°sF range.

The result was that the frogs started producing eggs again during the first summer of being in the new tank. They did it again the following spring and, even after the males had passed away, there was at least one female who expelled unfertilised eggs in April of one year. Unfortunately, I didn't keep detailed records.

The experience was unexpected and an unintended consequence of relocating the frogs. The main lesson I learnt from it is that what we may perceive as a "natural" tank can sometimes amount to little more than a pleasing visual effect to satisfy our own aesthetic requirements rather than a true replica the frogs' natural conditions.

[mpmistr]

They live in turbid water so this makes sense actually.