Algae in Aquaria


You have hit on a good question in asking whether algae is a bad thing.

The bottom line is that it is entirely natural, and all aquatic plants are
covered with the stuff in the wild, and to some extent they are modified or
adapted to deal with it.

For example, many long leaved aquatic plants normally photosynthesize most
efficiently near the growing tips, and the algae-covered lower leaves are
written off. Good examples include Hygrophila and the water lillies. In
trying to make these plants fuller, by encouraging lower growth and
preventing the plant getting tall, we are effectively working against the
natural growth of the plant. The net result is a continual battle to keep
the plant algae free.

By tending to overstock tanks compared with the "wild", aquaria become
eutrophic: i.e. very nutrient rich and attractive to emphemeral algae. You
can see exactly the same thing in polluted rivers and seas, where nitrate
and phosphate from farming, sewage and so on enter the water.

You can of course keep algae eating fish, but they are a two edged sword.
Putting aside any damage they do the plants themselves, they also excrete
and increase the potential for algal growth. Few people "factor in" algae
eaters to start off with...they are usually introduced like the Marines
when the crisis has already begun.

An aquarium decorated with algae can be very beautiful. In the UK, a number
of marine and freshwater varieties are sold, which are every bit as
attractive as vascular (true) plants. Large, smooth boulders with a rich
'aufwuchs' lit with strong lighting complement rift valley cichlids

All the best,



From  Neale Monks' Macintosh PowerBook, at...

Department of Palaeontology, Natural History Museum, London, SW7 5BD
Internet: N.Monks at nhm_ac.uk, Telephone: 0171-938-9007