Loricariad Catfish: A Primer
Plecos, or more properly, sucker-mouthed catfish, have perhaps the highest number of species of any family of fish in the Amazon basin, with over 780 known to exist in the family Loricariidae, with perhaps a third of them with scientific names. They are by far the largest family of catfish in the world.
Some are extremely common in the aquarium hobby, some rare, exotic and beautiful. Some are so weirdly formed they are so homely the can be considered cute. All have needs in the aquarium and none can thrive on only the algae in a tank.
In this primer I'll give a necessarily brief species list of the fish you are likely to find in shops, plus a few that can be found with a bit of searching and are worthwhile because of their looks.
None of the sucker-mouthed catfish in this list are particularly difficult to keep as long as a few essentials are provided, and all, especially the larger species, are very long-lived.
Now some species.
Perhaps the most common and miss-kept member of Loricariidae is Otocinclus vittatus, of the floating meadows in the Amazon basin.
Topping out at just over an inch, O. vittatus is imported in huge numbers, but few last long in the average aquarium. Though they are hardy when properly acclimated (drip acclimation, three to four cycles), they are rarely kept in schools of more than six fish like they deserve. They live far longer if kept in a group of their fellows, with more than five years not unusual.
They are perfect for the planted aquarium, and since they are accustomed to live plants in their natural environment, Otocinclus do best in them. Large-leaved plants like the big sword plants are a favorite haunt, and no fish will clean the top and bottom of the leaves like Otocinclus can. They will prevent algae from forming on the leaves of slow-growing plants like Anubis and Java fern. Their activities will keep plant-choking debris from settling on fine-leaved plants like Cabomba and Myriophyllum. Between a troupe of Otocinclus and a cadre of algae-eating shrimp, your planted aquarium will be algae free as long as that pair of creatures are in your tank.
They do best in the soft, slightly acid water of planted tanks, but will do fine in pH from 5.5 to 7.5, as long as the water is moderately soft. Temperatures are 70 to 78 degrees, with 75 being optimal.
They are excellent tankmates for schools of smaller tetras or rasboras. Since Otocinclus are so small, larger fish like Angelfish are out. Most dwarf cichlids are OK, especially Apistogrammas, since they are so mild about breeding. More aggressive dwarves like kribs and Convicts are most definitely out.
Though they have trouble with the hard, calcium-rich knots of algae on the glass, a troupe of Otocinclus will clear a green-algae covered tank in a day to a couple weeks, depending on the size of the aquarium. When they are nearly finished with the algae, it's time to feed them. Also, since they are starved on import, it is essential to get them feeding immediately, as Otocinclus drop like flies if not properly fed.
Vegetables are the rule, as the so-called algae wafers are poor fare indeed. Cucumber, Romaine Lettuce and and Zucchini are the big three with them. Cucumber slices can be sunk raw, the Romaine should be crushed so that the inside flesh is visible before clipping it to the side of the tank, and the Zucchini should be blanched until al dente. Any clean, hard or leafy vegetable can be used, so experiment to see what your Otocinclus tribe will take. Iceberg lettuce is useless, nutrition-wise, so don't use it.
Placing the vegetable foods in the same place night after night is a very good idea, as the Otocinclus group will quickly learn where to go for eats. As they do the majority of their foraging at night, place the foods just before lights out. Check them in the morning as it will be obvious if the Otocinclus have been working on the vegetables. Remove any that remains that evening before turning off the lights, as it's highly likely the Otocinclus will continue to feed on the veggies all day, because it takes a lot of greens to keep the little herbivores going.
Green algae is easily cultured on stones in a container that gets indirect sunlight and has an ammonia source, like a group of guppies. The stones can be rotated in and out of the Otocinclus tank as the fish clear them. Home-cultured algae plus the vegetables and your Otocinclus group will live long, healthy lives.
A group of Otocinclus will commonly breed when they are mature in the planted tank if properly fed and kept. If you see tiny single eggs the size of mustard seed all over the glass at one end of the tank, your Otocinclus group has bred. The eggs can be carefully scraped off the glass with a new, sharp double-edged razor blade, catching them as they fall into a brine shrimp net. Breeding tank should have a seasoned sponge filter and be filled with the same aquarium water as the main tank. Tank should be 10 to 20 gallons and bare bottomed. Tint the water with Methylene Blue to discourage fungus.
Eggs should hatch within three days at 76 degrees and it'll take two more days for the fry to be free swimming. Feed them algae covered stones and crushed Spirulina flake. Keep the tank very, very clean and change 50 percent of the water four times a day. The Otocinclus fry should be half grown in six weeks.
A larger, distant cousin of Otocinclus, is Hypoptopoma gulare, which also frequent the floating meadows of the Amazon as well as submerged vegetation in Peru, Columbia and Venezuela.
Topping out at three inches, one MUST drip acclimate this species AT least four cycles, as they are quite delicate after the starvation and stress of shipping. Crushed fresh spinach leaves rubber-banded to stones and placed with the leaf on the substrate, just before lights. out will help your H. gulareget back on their feet.
Well established, however, H. gulare is very hardy. They are also long lived, as the 12 I have were purchased 8 years ago.
Gulare needs somewhat more roughage than their smaller cousins, so add leaf spinach and kale to the menu. A vegetative pellet containing kelp and spirulina will be taken if a few pellets are dropped in at night. Because they are larger, they need appreciably more vegetative food available 24/7 than Otocinclus do. My 12 can polish off a dozen fist-sized algae-covered rocks in an evening.
They are affable fish; perfectly peaceful. Tankmates can be small to larger tetras or rainbow fish. To my experience Angelfish will either leave the gulare group alone, or pester them mercilessly, so use these fish with caution.
A pleasing mix of a brown chocolate in a herring-bone pattern on the back 2/3rds of the fish with a greenish lower area, H. gulare is often called Giant Otocinclus in the trade, though it is of a different Genus all together and not closely related to Otocinclus. Eyes are a brown-golden.
They are an excellent addition to the larger planted aquarium, especially those with large-leaved plants and driftwood, as part of their diet will be the bio-film on the wood. They are also very good cleaners of plant debris.
They do best with a moderate linear current in the tank, as their sloping heads are designed to push them down on the algae they feed on in nature, and will be far more active if you provide it. Also, they need no less than 8 mg/l dissolved Oxygen in their tanks. In a planted tank, that's rarely a problem, but aireation should be employed at night to keep O2 levels high. Gulare do not do well in tanks over 7.4 in pH with moderate hardness; the bright neutral to slightly acid softwater tank is what they enjoy. Temps are 75 to 78 and no higher than 79.
H. gulare is perhaps the most efficient algae eater you can buy, as not much escapes their notice. They won't touch Cyanobacteria, but they will make inroads on black brush and other red algae, and will quickly eliminate diatoms and of course green algae.
They breed like Otocinclus do, but mine didn't start breeding until they were in their third year. The fry aren't difficult to raise if fed and kept as above, but it is even more desirable to breed these fish as they are rarely imported, as they are such good algae eaters and rare in shops.
Last edited by Dave66; 07-10-2008 at 07:41 AM.
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