A few years ago, I placed several Ancistrus temminckii in my largest (150-gallon) aquarium. This is a very busy, well-stocked community aquarium, and I was reasonably sure that the Ancistrus would not be comfortable breeding in this aquarium. For several years, that was the case, and my swords were lovely.
Recently, however, the Ancistrus began to breed explosively. I now have a population with dozens of Ancistrus of all sizes in the aquarium. The Ancistrus (a.k.a. bushynose pleco, bushynose catfish, bristlenose catfish) is a dwarf Loricaridae that matures to a length of about 4 to 6 inches. It generally does not eat plants but is very effective at scrubbing algae off many kinds of surfaces, including plant leaves and driftwood. It grazes on driftwood (many Loricaridae actually need some wood in their diet). The daily algae consumption of one Ancistrus easily is more than that of a dozen tiny and cute Otocinclus in a month. With one or two in your aquarium, their gentle grazing on live aquatic plants generally is not a problem; it takes a lot of grazing by Ancistrus before the leaves of, for example, E. bleheri show any signs of wear. Wear usually shows only on older leaves that need to be pruned, anyway.
I recommend Ancistrus if you are looking for an effective anti-algae fish. But if you have both a male and female, watch out for their propensity to breed like bunnies. Former Aquarium Fish International plant columnist Karen Randall reminded me recently that the Farlowella acus can be a helpful Loricaridae, and it does not breed so easily. This stick-thin fish can grow to about 9 inches and needs a vegetable diet. So, a small aquarium will provide enough room or algae. Their diet can be supplemented algae wafers or blanched zucchini. Some “plecos” will eat your aquarium plants outright, and some, including dwarves like the Pekoltia and the zebra (Hypancistrus zebra) actually prefer a meaty diet and so are not very good at consuming algae. Many Loricaridae can get very large, eventually a foot or longer, and just one can be more damaging to aquatic plants than several Ancistrus.
If you have a large Ancistrus population and the grazing wears thin, the recourse is to put in some bottle traps and remove the Ancistrus. If I favored Ancistrus more than the plants, I would not have to remove them, but remove them I will; for among my favorite aquatic plants are the swords, plants of the genus Echinodorus, the kind of plants that the little raspers affect most.
The different Echinodorus provide a variety of shades of green and some spectacular red colorings, too. Many hybrids exist that combine several desirable features in one plant. For example, E. “Orientale” offers a delicate rose tone and E. “Kleiner bar” is a small sword bearing a ruddy burnt sienna. Most of the Echinodorus grow too large for very small aquaria. However, in an aquarium without any added carbon dioxide (CO2), some of the larger species, like E. bleheri and “ozelot,” will grow slowly and remain small for many months, helped with vigorous pruning of the outer leaves. The best way to prune a sword is to peel and pull an outer leaf as close to the base as possible.
The most commonly available and perhaps easiest to grow of the swords is E. bleheri. This is a beautiful medium green plant with long spearhead shaped leaves and very small petioles when grown submerged. For red color, the E. “ozelot” has a mix of red and green, and the red is especially intense on the younger leaves and under bright light. Under optimum conditions (good light, added CO2 and plenty of nutrients), either of these can grow to about 8 to 16 inches in length. Another easy to grow Echinodorus is the hybrid “Rubin,” however the Rubin, like the cordifolius, can easily grow to 20 inches or more and become the centerpiece, endpiece and frontpiece of your aquarium all at the same time – they get very big. Vigorous pruning can help retard their growth, but they seem determined to be big aquatic plants. The Rubin is a beautiful red sword.
At the other end of the spectrum, the E. parviflorus “Tropica” grows to only about 6 inches if given plenty of light (e.g., more than 2 watts per gallon of high-quality fluorescent lighting) and stays much smaller under less light. It is a sword suitable for the foreground in many aquascapes.
The species angustofolius has an appearance like long grass. It can grow up to a foot tall under good light but will tend to remain much shorter under less light. It spreads rapidly by runners, and you have to clip and remove, or relocate, the runners to control the spread of the aquatic plant.