Plecos and Algae Eaters: Choosing the Right Cleanup Crew

Algae Eaters Don't Replace Cleaning

OATA makes the point plainly: algae-eating fish aren't a substitute for regular maintenance and sensible stocking, and persistent algae usually points to a water or maintenance problem. Fix the cause first; see cloudy water fixes.

Every algae eater also needs its own food, such as algae wafers and fresh vegetables like cucumber or zucchini (courgette). OATA advises washing vegetables well or buying organic, as pesticide residues can harm fish and shrimp.

The Common Pleco Problem

The "common pleco" sold as a small, cute algae eater is several large species that can grow well over 12 inches (30 cm), with recorded lengths over 16 inches (40 cm). OATA lists the larger plecos among "tankbusters": fish that outgrow standard aquariums and live a long time. Unless you have a very large tank, choose a small species instead.

Better Choices for Most Tanks

• Bristlenose catfish: about 6 inches (15 cm). Alone, in pairs or small groups with one male. Males have bristles on the nose. Needs cover and at least one piece of wood to graze.
• Clown pleco: rarely over 4 inches (10 cm). Alone or as a male and female pair, as males fight. Needs wood in the tank as part of its diet.
• Otocinclus: about 1.6 inches (4 cm). Keep five or more in a calm, planted tank with clean, well-oxygenated water.
• Amano shrimp: up to 2 inches (5 cm), in groups of five or more. Very sensitive to copper; see freshwater shrimp and snails.

OATA gives these species about 72–81°F (22–27°C) and pH 6.0–8.0; shrimp tolerate about 63–81°F (17–27°C).

Feeding Algae Eaters

Offer sinking algae wafers in the evening, when plecos are most active, and blanched vegetables a couple of times a week. Remove leftovers the next morning. Bristlenose and clown plecos also need wood to rasp on.

Tank Mates and Setup

Most small plecos are peaceful with community fish but may squabble with each other over caves. Give each one a cave or hiding place, and keep otocinclus away from boisterous or large fish. Plecos are mostly active at night, so don't worry if you rarely see them by day.

Keeping Them Healthy

Most problems in small fish start with water quality. Test ammonia, nitrite and nitrate weekly, change about a quarter of the water each week with conditioned tap water, and rinse filter media in old tank water, never under the tap. Quarantine new fish if you can, and add them a few at a time so the filter keeps up.

Watch your fish every day at feeding time. Changes in swimming, color, breathing or hiding are early signs that something is wrong, so test the water first.

For fish treatments or medicines: see your vet or a pet supply store with trained staff. An aquatics store with trained staff, or a vet who treats fish, can help you work out what's wrong before you add anything to the tank.