'Algae' is often preceded by various words not to be repeated in polite company, suffice to say it is a problem encountered by most fishkeepers 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 it
Algae 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 eaters
The 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 'Suckermouth' 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 suckermouth 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. Suckermouth catfishes will usually avoid established fiberous, brush, or blue-green algae but will help to prevent its formation.
Some suckermouthed catfishes can be territorial and may squabble but damage is rarely done providing each fish has its own retreat and all will mix with tankmates of any size within reason. Although there are cases of some suckermouthed 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.

Hired thugs
The majority of loaches are primarily scavengers but there are a few which are very good algae eaters. Unfortunately they often turn out to be a bit of a loose cannon, exhibiting undesirable and sometimes unpredictable behaviour. The 'shark' group of loaches including the ruby sharks and red-tailed black sharks (Epalzeorhynchus sp.) all have aggressive tendencies particularly towards each other and must be kept either singly or in larger groups to avoid a single dominant bully. It is a certainty that a pair of fish within this group kept together will continually fight but it is not so easy to determine how they get on with other fishes. In a significant number of cases these fish can become aggressive bullies within a community so they are best kept only with sizeable tough and active fishes. In terms of behaviour, the popular loach Gyrinocheilus aymonieri, often called Chinese, Siamese, or Indian algae eater is very similar and can become more of a pest than a useful addition. In many cases this fish can attack other fishes if it develops a taste for mucus. Although problematic, these fish should not be excluded from aquarium life, just mixed sensibly with other fishes. The sharks will have a go at most types of algae, occasionally including brush and fiberous algae but the real force in this group is the siamese flying fox (Crossocheilus siamensis) which will eat almost any algae and is particularly good at reaching the parts other algae-eaters don't.

Peacekeepers
Livebearers are not often sold for the purpose of algae eating but are in fact rather good at it, particularly the mollies and platies. The best thing about these fish is that they are small, peaceful and are very gentle feeders so are unlikely to harm plants as they take algae from the leaves.
There are also some inverts that are very good algae eaters. Snails can be quite useful but are usually a pest in the aquarium due to their ability to rapidly multiply. The large apple snails (Ampullarius sp.) are a good choice though as their size makes then easy to spot and remove should they decide to breed. These large snails may damage more delicate plants however so may not be suited for some aquaria. For the underwater gardener there is no better algae eater than the Japonica shrimp. Providing there is nothing big enough to eat these small shrimps, they can be a godsend and will eat virtually any algae without harming even the most delicate of plants. The only drawback with these shrimps is that you may need quite a big team to get the best results.
The war on algae will always continue, but the recruitment of a group of algae eaters will greatly improve your chances of success. Make sure you select your fishes carefully though, or your aquarium could become an even bigger battlezone.

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