Aquarium 'Muck'

In the gravel at the bottom of any aquarium there accumulates a lot of 'muck' that you may will occasionally clean out. It looks pretty disgusting and useless!

However: this muck is in fact a whole biological ecosystem of micro-organisms: bacteria, protozoa, rotifers, worms and much more, living on the fish excreta, dead plant remains, decaying fish food and whatever else it can find. If the aquarium is to be healthy, these organisms are not only present but are absolutely necessary. They will get there of their own accord, for most of them are propagated by air-borne spores.

However it's probably a very good idea to seed the gravel with a small amount of bottom mud from a pond: one that does not contain fish will probably appeal to most people as it minimises the risk of introducing any thing harmful.

There are several larger organisms that can safely live in this bottom mud and help it function: in ponds you can often find aquatic worms, relatives of the common earthworm. The tubifex you may feed your fish is but one: there are others, some 2-3 cm long and looking very similar to earth worms.

These worms are fine inhabitants of the gravel: if the fish find them, they will get eaten. If not, they wil breed and help work the gravel.

This gravel much can also be a very good source of food: I had a Black Molly litter of in excess of 50 babies. Since most will get eaten, I put about a dozen in a trap. Now normally when I've done that the ones that are not in the trap thrive better and get fatter faster (until they get eaten), as they have more microorganisms to catch in the main body of the tank.

As an experiment, I siphoned some of this gravel muck and used it as a substrate layer in the trap. The babies love digging in it, and this time they are growing slightly noticably than the babies in the main body of the tank.

Occasionally I dig out the microscope. With its help I will list the organisms living in the muck, as I find and identify them. They are of two sorts: those I did not introduce deliberately and those that I know I did introduce, usually the larger animals.

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Last modified: Fri, 24 Nov 2017 12:09:59 GMT
Page first published 14th December 2002.
Page written and © by Richard Torrens