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    Species: Otocinclus - great algae eaters

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    Species: Clown Loach - the snail hunter!

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    Species: The Bristlenose - another good algae eater

  • Species: Platydoras costatus - will eat snails

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    Species: Corydoras - good ground cleaners

The Cleanup Crew

Maintaining an aquarium can, on the one hand, be viewed as the opportunity to watch a little window onto the wonders of nature, with living jewels darting among luxuriant and beautiful water plants. This is the view most of us aquarists have, most of the time. On the other hand it can be viewed as keeping a device of which the sole purpose is to produce a range of unpleasant sludges and slimes. At the end of a long day, when filter cleaning has rolled round again, it seems astonishing that a few little fish can produce such quantities of brown sludge, and it is also mystifying how while your plants look as though a plague of locusts has just passed through, green algae is flourishing on the glass and happily coating the poor little stubs of your once-healthy foliage.

Unfortunately, this is all a fact of life. Simple (and usually undesirable) organisms like algae and a host of bacteria are pretty tough, and will flourish regardless of conditions, whereas the animals we actually want are not only a great deal more particular about their requirements, but are actually little mess-producing factories, taking in expensive fish food at one end and happily sending most of it out the other end as sludge. There is no escaping the filter-cleaning, the water-changing, all the other regimes necessary to keep toxins at bay in the closed systems that are our aquaria.

What there are, however, are a number of organisms that make our lives that little bit easier, although it is worth noting that these too do their share of excretion. The smallest of these are, of course, the bacteria that live in your filter. The ammonia – nitrite – nitrate cycle is the result of their constant appetites and equally constant excretion. These are the most useful of the inhabitants, but they aren’t much fun to keep, being invisible. Among the higher organisms (i.e. the ones you can actually see doing things) there are a number that can make particular problems that bit less taxing,

The build-up of nitrate in the water is the result of successful and healthy filtration, and is unavoidable. Worse still, in some areas the tap water can also be high in nitrates, so water changes don’t necessarily fix the problem. Plants do consume nitrates, so you would think that planting the tank thickly would be the answer. However, although all the plants in your tank are feasting away, they are still in your tank. As leaves die, the food and energy taken up to produce them is released back into the cycle. A good way round this is to keep a particularly rampant plant. Duckweed is ideal for this, although difficult to eliminate if you change your mind. Elodea is another fast grower. As the plants take in nutrients and use it to produce new growth, you can remove it from the tank simply by taking out handfuls of plant and throwing it away. As each net load of duckweed hits the bin, it takes with it all the plant nutrients that went into creating it.

One of the main irritations with an undergravel filter is the way that without careful and regular cleaning it can compact into a solid mass of sludge embedded with gravel. Once this happens, it will stop working, as the water can no longer flow through it easily. To counteract this problem, a variety of devices are on sale, ranging from tiny little vacuum cleaners to a more simple attachment for your siphon tube, all designed to stir it up, get some of the sludge out, and let the water flow through to those hungry little bacteria. What you really need is something that will keep stirring the gravel up and loosening it – which could possible be trumpet snails. Trumpet snails get a mixed reaction. For some people they arrive as uninvited guests, who once through the door are impossible to get rid of again. Other people actually pay money for them. However yours arrive, once you’ve got them you might as well learn to love them, as the only way to get rid of them is to throw away all the tank contents and start again. Like the duckweed, this is not a decision to be taken lightly. But once installed, the trumpet snails will devote their lives to turning over the gravel bed. During the night they will come up and be active in the tank, but during the day they spend their time moving through the gravel, eating lost particles of food and doing what snails do best, which is making more trumpet snails. This can serve as a useful indicator of whether you are feeding too much – if there is a lot of extra food, the population will explode. You can, however, use the duckweed principle for removal – after lights out you easily can scoop out and bin trumpet snails. The other good thing about them is that, unlike other aquarium snails, they won’t touch your plants.

But what if your problem is snails? A couple of nice little pond snails, that you thought would add the finishing touch, or even a little jelly clump of eggs hiding on a new plant, can be the start of a plague. One or two snails can become a hundred within a rapid space of time. Within a few weeks, your plants all look like lacework, the filter is clogged with snails, and everywhere you look there are tiny little shells with chomping mouths. Unfortunately the answer is that you can’t do much, other than take them out when you see them, and keep to a very strict feeding regime. Proprietary snail killers leave your tank full of dead snails, which is even worse than live ones. Contrary to the instructions, mine have never floated to the top conveniently after treatment, and there always seem to be some hardy individuals who can survive anything. The sensible answer would be to choose something that eats snails. Although many people report an astonishing array of fish that crunch their way through snails, with clown loaches being one of the most often recommended, the only thing I have ever found that would eat snails in anything other than direst extremity was a puffer fish. Since they also grow big and eat everything else as well, including your little fish, this is hardly a practical solution. Talking catfish (Platydoras costatus) do eat snails, but aren’t exactly agile – they won’t go clambering among the plants to find them. They are attractively patterned, which makes it particularly irritating that they usually only come out in the dark. The only real answer is to take everything out of the tank, boil what you can (except the fish!) and throw the rest away. And the new plants you buy might still come with a free little jelly clump attached, so a good soak in potassium permanganate solution is a sensible preventative.

One of the most irritating problems is green algae forming a coat over everything. A little bit may be quite appealing, giving a tank a more natural look, but when you can’t actually see your fish because there is a green curtain across the glass the charm of the natural look wears off. When you do procure a razor or scrubber and clear a window, you find that the plant leaves are also all covered, so the poor little things aren’t getting any light. Your tank is still a planted one, but now it’s planted with algae. The answer to this is, fortunately, a simple one. There are lots of fish that just love to eat algae. The South American loricariids are among the most popular, but do exercise care – many can grow to giant size. Plecs do eat algae, but the odds of a foot long fish managing to perch on your plants to clean them are minimal. Once they exceed a few inches, they produce huge quantities of waste and do very little work. Bristlenose catfish are interesting and tireless labourers – a pair is quite capable of keeping a four foot tank free of the dreaded green slime. Although they are designed for a vegetarian diet, they don’t turn their noses up at other foods, and will also helpfully remove the small corpses that do occur from time to time even in the best kept tanks. Even healthy fish are not immortal, and a rotting carcass can quickly pollute the water. Otocinclus are another good buy, and suitable for smaller aquaria. A group of these little fish will not use up too many of your ‘fish inches’ and will do an excellent job for you. A word of warning – don’t starve the poor things to make them keener on the algae. A piece of cucumber or some algae pellets will keep them fit and well, and they will still work away at cleaning the glass and décor. One to avoid is the Gyrinocheilus aymonieri, an unpleasant fish that rapidly loses its taste for algae and has a nasty tendency to acquire one for rasping at the sides of other fish. This fish is often sold as the Siamese or Chinese algae eater, which is unfortunate, as the real Siamese algae eater, Crossocheilus siamensis, is a much better buy. This latter is one of the few fish that will tackle brush algae.

Sometimes a variety of small pests can arrive by accident in your tank. Tiny white or brown worms can be a result of overfeeding, and are usually harmless and will die back when you correct your feeding regime. Hydra, little tubes with an outcrop of filaments at one end, are harmless to adult fish, but not a good tankmate if you hope to have little fry. Tiny fish make a tasty snack to lots of things, and hydra are one of them. The blue gourami is a hardy and attractive fish who is happy to clean up many small invertebrates, and is reputed to also snack on snails (if you’re lucky, this is an added bonus).

Bottom-feeding fish help keep the tank clean by hoovering up the pieces of food that fall past the fish feeding at the top. The bristlenoses mentioned earlier are good at this, and another group of catfish, the Corydoras, are cute as well as spending nearly all their time checking the tank floor for goodies. Uneaten food is a rapid tank polluter. However, do bear in mind that keeping the tank floor pristine is especially important with these fish – they will do a good job for you, but if you let pollutants build up then the fish who spend their lives at the bottom will be the first to be affected.

A careful choice of aquarium inhabitants can go a long way towards making your life that bit easier, and indeed the lives of your fishes. Nonetheless, do remember that there is no fish, snail, or any other creature who can counteract the effects of bad hygiene and maintenance!

This article has been kindly provided by Kathy Jinkings and cannot be reproduced without her permission.

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