Subterranean Fishes of the World

3091

2015

AIM 2015

Astyanax mexicanus is a model cave-dwelling fish with sighted surface-dwelling (surface fish) and blind cave-dwelling (cavefish) forms. Although it is relatively easy to make them spawn in the lab comparing with other non-model system, it is sometime hard to do so especially at the newly established system. Here I present a simple and a cheap way to build the system. The key features required for the system are: (1) water-flow, connecting multiple tanks into one, (2) tight temperature control by a heater and a chiller, (3) filtered water from reverse-osmosis system, and (4) rough surface at the bottom. For (1), female Astyanax seem to release chemical (pheromone) when they are ready to spawn, that stimulate other fish. If you have multiple tanks connected to each other, it will raise the chance of spawning events. Also, you need one sump for such water flow system, making it easy to regulate water chemicals. In addition, I will talk about a hand-made sump system, which filter and maintain the water quality enough. For (2) the tight temperature control, Astyanax mexicanus are tropical fish, sensitive to the change of the water temperature as low as 1°C shift. Therefore, the combination of heater and chiller stabilize the temperature better at 22°C, which is a maintaining temperature for the Astyanax. For (3) about the water source, the reverse osmosis system stabilizes water chemicals. We add the pH conditioner and sea salt for conditioning water at pH ~7.0 and conductivity at 600 μS. As for (4), the rough surface at the bottom of the tank has not been thought as an important factor. In our observation, surface fish spawn after introducing the spawning net, which has a course net on the top and fine net at the bottom, making easy to recover spawned embryos. Perhaps female prefers the rough bottom surface because it can give embryos a better chance to avoid to be eaten by conspecific or others. Our current system houses 18 of 10 gallon (38 L) tanks connected to a 40 gallon (150 L) sump tank. We feed TetraColor Tropical Granules and dried shrimp, and our fish routinely spawn every other week. We also provide the technique how to make spawning nets.

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