Siamese Algae Eater Care: Tank Setup, Feeding, and How to Spot the Real Fish

The Siamese algae eater is one of the few fish that actually eats black beard algae. That single fact makes it a prized addition for planted tank keepers battling stubborn growth.

Quick Answer: The Siamese algae eater (Crossocheilus oblongus) grows to 6 inches, needs a 30-gallon tank minimum, and thrives at 75–79°F with a pH of 6.5–7.0. It's the only commonly kept freshwater fish that reliably targets black beard algae (BBA). Keep a group of 5–6 for the best results.

What Is a Siamese Algae Eater?

The Siamese algae eater (Crossocheilus oblongus) is a peaceful, active bottom-dweller native to fast-moving rivers in Southeast Asia. It originates from the Mekong basin across Thailand and Malaysia [1].

It's famous for one key trait: it eats black beard algae. Most algae eaters won't touch BBA. SAEs do.

Quick Stats

SAEs are schooling fish. They do best in groups of 5 or 6. A lone SAE becomes shy and stressed.

Their Natural Habitat

According to FishBase, SAEs inhabit fast-flowing rivers with rocky substrates and heavy vegetation [1]. They're built for high oxygen levels and moderate current.

This matters for your tank setup. SAEs need strong filtration and surface agitation to stay healthy.

Pro Tip: Add a powerhead or circulation pump to boost water flow. SAEs stay active and healthy in tanks with noticeable current and well-oxygenated water.

Siamese Algae Eater vs. Flying Fox: Don't Buy the Wrong Fish

This identification test is the most important thing to know before visiting a pet store — stores routinely mislabel flying foxes as Siamese algae eaters. Only the true SAE eats black beard algae [2].

The two fish look nearly identical. But the differences are clear once you know what to look for.

How to Tell Them Apart

Common Myth: "All fish sold as SAE in pet stores are true Siamese algae eaters." Reality: Many stores stock flying foxes or Chinese algae eaters under the SAE label. Flying foxes grow aggressive as adults and ignore black beard algae entirely — the opposite of what you want.

The quickest field check: look at the tail fin. If the black horizontal stripe extends into the caudal fin, it's likely a true SAE.

Check out our complete algae eater species comparison to see how SAEs stack up against other popular algae-control fish.

Tank Setup and Water Requirements

Siamese algae eaters need at least a 30-gallon tank, but 55 gallons is better for a group of six. They're fast, active swimmers that need room to school and forage [2].

Water Parameters to Maintain

Keep these ranges consistent:

• Temperature: 75–79°F
• pH: 6.5–7.0
• Hardness: 5–10 dGH
• Ammonia: 0 ppm
• Nitrite: 0 ppm
• Nitrate: Below 20 ppm

A reliable heater with a thermostat keeps temperature steady. See our best aquarium heater picks for options matched to different tank sizes.

Filtration and Flow

SAEs need strong filtration. They produce moderate waste for their size.

A canister filter or hang-on-back (HOB) filter works well. Target 8–10× tank volume turnover per hour.

Decor and Plants

SAEs thrive in planted tanks with the right mix:

• Dense background plants — they graze naturally on leaf surfaces
• Smooth river rocks — mimics their native rocky riverbeds
• Driftwood — biofilm grows on wood and provides extra grazing
• Open midwater lanes — SAEs are fast swimmers and need space to zip through

Avoid sharp decorations. SAEs brush against surfaces while foraging. Sharp edges cause fin damage over time.

Pro Tip: SAEs are skilled jumpers. They can easily clear several inches of open water. Always use a tight-fitting lid and check for gaps around filter tubes and airline lines.

As of May 2026, planted tank community consensus holds that SAEs behave best in tanks with both dense planting zones and open swim corridors — not one or the other.

What Do Siamese Algae Eaters Eat?

SAEs are omnivores that eat algae, biofilm, detritus, and most prepared aquarium foods. Their dietary flexibility is one of their best traits as a community fish [3].

Algae They Actually Target

This is where true SAEs outshine every other algae eater:

The critical rule: don't overfeed. A full SAE ignores algae. Keep prepared food portions small.

Prepared Foods to Offer

Supplement their algae grazing with:

• Sinking algae wafers — the most important prepared food for bottom-dwelling algae eaters
• High-protein sinking pellets — supports muscle and long-term health
• Blanched vegetables — zucchini rounds, cucumber slices, or spinach leaves

Feed once daily. Remove uneaten food after 10 minutes to keep water clean.

Common Myth: "SAEs can live on tank algae alone." Reality: An algae-only diet causes nutritional deficiencies over time. SAEs need protein and varied nutrients to reach their full 8–10 year lifespan.

For a broader look at controlling algae naturally, read our aquarium algae problems and solutions guide.

Compatible Tank Mates for Siamese Algae Eaters

Siamese algae eaters are peaceful community fish that pair well with most non-aggressive species. They spend most of their time near the bottom and lower midwater.

Great Tank Mate Options

• Small tetras — neon, rummy nose, cardinal, ember tetras
• Rasboras — harlequin, chili rasbora, galaxy rasbora
• Corydoras catfish — share the bottom level peacefully
• Dwarf cichlids — German blue rams, apistogramma species
• Livebearers — platies, mollies, endlers
• Amano shrimp — see our amano shrimp care guide for why these two make a powerful algae-control team

Tank Mates to Avoid

• Large aggressive cichlids — will bully or eat SAEs
• Fancy goldfish — require cooler water than SAEs prefer
• Multiple large competing algae eaters — causes stress in smaller tanks

SAEs generally leave adult shrimp alone. Nerite snails are completely safe tank mates. Check our nerite snail care guide for more on pairing these two species in planted tanks.

Common Mistakes New Keepers Make

Most SAE problems trace back to three errors: buying the wrong fish, keeping singles, and overfeeding. Avoid these and your group will thrive for a decade.

Buying a Flying Fox Instead

This is the most frequent mistake in the hobby. Flying foxes sold as SAEs:

• Won't eat black beard algae — the whole reason you wanted one
• Turn territorial as they mature past 3–4 inches
• Chase and stress smaller peaceful tank mates

Always use the tail-stripe test at the store before buying.

Keeping One SAE Alone

A lone SAE shows these stress signals:

• Hiding behind rocks or plants constantly
• Faded or dull coloration
• Erratic darting or twitching movements
• Refusing prepared food

Keep a minimum of 3 SAEs. Five or six is ideal in a 55-gallon setup.

Overfeeding Your SAE

Overfeeding trains SAEs to ignore algae completely. This defeats the purpose.

Limit prepared food to once daily. Give only what the fish finish in 5–10 minutes.

Skipping the Lid

SAEs jump. They do it often and without warning. Many hobbyists lose fish to uncovered or loose-fitting lids.

Use a glass canopy or solid mesh hood. Block all gaps around filter tubes and airline lines.

Pro Tip: If your SAE group suddenly hides more or loses color, test your water immediately. SAEs react fast to elevated nitrates or ammonia spikes. A 20–30% water change usually restores normal behavior within 48 hours.

Where to Buy SAE Supplies

Shop now for the best Siamese algae eater essentials:

• Canister or HOB filter: Top-rated aquarium filter on Amazon
• Submersible heater: Best submersible aquarium heater on Amazon
• Sinking algae wafers: Best algae wafers for bottom feeders

These three products form the foundation of a proper SAE setup.

Sources

1. FishBase — Crossocheilus oblongus
2. Seriously Fish — Crossocheilus oblongus Care Sheet
3. Fishkeeping World — Siamese Algae Eater Diet and Care