Another Source of Carbon for Tropical Fish – Deep Sediment Methane
We are all familiar with the common way fish get the building blocks they require – through their diet. But most assume that the food they eat is derived from carbons that are all organic in nature and found as part of the plant and animal materials that are available in the surrounding environment. It has long been known that deep sediment methane is produced deep in lake beds and it has been concluded that it is pretty much deposited there permanently in the slowly building substrate falling to the bottom over time.
In a new study, though, it has been determined that carbon from aerobic organisms, such as plants, insects and fish, usually derived from carbon dioxide in the environment as well as incorporated into the tissues of other animals and bacteria is not the only carbon source. The methane produced, and previously thought permanently trapped is also a source of the carbon that works its way up the food chain to feed the fish. It has not been easy to document this source of carbon as the testing devices were unable to corroborate previous findings.
New research in Brazil and recently published does show that there is a link between the deep anaerobic substrate in a lake and the fish that are swimming in it. The study concludes:
Methane is taken up by methane oxidizing bacteria, which in turn are eaten by zooplankton and other aquatic organisms. These organisms eventually end up in fish stomachs, meaning that food webs not only feed off organic carbon from plants in the lake or from the surrounding land; but also from deep-lying and oxygen-free, yet carbon-rich, sediment stores where methane is formed.
Deep Sediment Methane is Not a food for Aquarium Fish
This may be a very important finding for lake ecology and habitat study. I am sure it has impacted many fish species and been a major factor in their nutritional requirements. Ensuring an active and viable population of anaerobic bacteria that convert methane into tissue of zooplankton may be a very important finding. But don’t expect new foods featuring these zooplankton or deep sediment methane fed insects to hit the store shelves as a new food for your aquarium fish. In a tank, anaerobic pockets can be quite deadly as they release bubbles of toxic gas that move to the surface. The transitory nature of an aquarium, when compared to the eons most lakes survive means that this type of finding is not going to impact our hobby in any major way.