Algae Eating Species
'Algae' is often preceded by various words not to be repeated in polite company, suffice to say it is a problem encountered by most fish keepers at some point. The solution is not straightforward however and there is no 'quick fix' answer to the problem. Instead, it is often best to look for a long-term plan of attack. Part of the remedy is the employment of a good team of algae eaters.
It's a tough job, but somebody's got to do itAlgae is not a great source of food, if it was, all fish would have a nibble. Algae is tough, hard to digest, and produces minimal nutritional value. For most algae-eating fish, algae is only part of their natural diet and in some cases they only eat algae to get the bugs which live amongst it.
In the aquarium this means that algae eating fishes must be given additional sources of food usually in the form of sinking pellets or wafers.
The majority of algae eaters will also only consume certain types of algae, most will not eat fiberous stringy algae or black/brown fur-like brush algae and very few if any will eat the velvety blue-green algae which forms a 'carpet' over plant leaves and substrates.
To get the best results, a combination of algae eaters need to be employed, but some common algae eaters come with there own difficulties, luckily there are many alternatives.
Evolved eatersThe best-known 'traditional' algae eater is the common plecostomus, but this particular fish is a heavyweight contender and will grow to huge proportions (45cm 18"+) so is suited only to the very largest of aquariums.
A good alternative is the bristlenose plec (ancistrus sp.), which is very similar in appearance, yet only reaches a manageable 15cm (6"). Bristlenose plecs are one of the suckermouth catfishes (Loricarids), which have evolved to eat algae as their primary food source.
The 'Sucker-mouth' is a highly developed mouth that will rasp away at algae but is also used to scrape off the very top layers of established driftwood. The driftwood eaten by the fish is actually an important part of its dietary and feeding systems so to keep any of the suckermouth catfishes it is a vital piece of decor.
There are many other sucker-mouth catfishes to consider, including some colourfully marked unclassified 'L number' fishes. It is worth trying to find out as much as you can before purchasing, as some of these fish may require soft water or may grow to significant sizes.
A couple of good choices for the smaller aquarium would be the otocinclus sp. or peckoltia sp. (dwarf plecs) Both these groups of fish are peaceful and the biggest will grow no bigger than a few inches. Sucker-mouth catfishes will usually avoid established fibrous, brush, or blue-green algae but will help to prevent its formation.
Some sucker-mouthed catfishes can be territorial and may squabble but damage is rarely done providing each fish has its own retreat and all will mix with tank-mates of any size within reason. Although there are cases of some sucker-mouthed catfishes attacking fish, particularly laterally compressed species (angelfish, gouramies etc.) these are rare and usually occur when the victim fish is producing excess mucus due to illness. It would be tempting fate however to mix these fish with discus which are slow moving and produce a particularly tasty brand of mucus.