Siamese Algae Eater UK: The Complete 2026 Planted-Tank Guide

Why this page exists — and why every other SAE guide gets the basics wrong

Most "Siamese algae eater" Google results are written by people who have never identified the species in person. They confuse four similar-looking fish, recommend groups that don't work, and skip the single crucial fact about the species: it's the only fish that eats black beard algae.

I'm James. I've run planted tanks with SAEs through two BBA outbreaks and one hair-algae surge. This is the version of the guide I'd send to a friend who just bought a CO₂ rig and is seeing the first black tufts on their driftwood.

A Silver Flying Fox (Epalzeorhynchos kalopterus). Note the yellow and black fin markings — the immediate tell that separates this from the real Siamese algae eater, whose fins are clear. Photo: Tropical Fish Co warehouse.

Five facts most "SAE buying guides" miss

• "Siamese algae eater" used to mean four different species. The taxonomic revision in 2019 split what was historically sold as a single species into multiple distinct species — Crossocheilus oblongus, C. siamensis, C. atrilimes, and several others ^[3]. Most UK stock is now confirmed C. oblongus.
• SAEs are the only fish that eats black beard algae. Not exaggeration — it's genuinely the only species in the UK freshwater trade that grazes BBA. This is the main reason planted aquascapers keep them ^[4].
• Real SAEs have NO colour on their fins. Their fins are clear or very pale grey. If you see red, yellow, orange, or strong black markings on the dorsal, tail, or pectoral fins — it's a false SAE ^[5].
• They can live 10 years. Well-kept adults in a stable planted tank routinely reach 10 years old ^[1].
• They tolerate the full UK tap-water range. Hardness from 5 to 20 dGH and pH from 6.5 to 8.0 ^[1], which means every UK postcode's tap water works ^[6].

How to tell a real Siamese algae eater from a fake one

This is the single most important section of the page.

Head-to-head: the four fish sold as "Siamese algae eater" in UK shops

The single diagnostic is the tail stripe + fin colouration. If the stripe stops at the tail base, it's not the real SAE. If the fins have colour markings, it's not the real SAE.

The black beard algae problem — why you bought this guide

A Snow White Bristlenose Pleco. Plecos and SAEs work in tandem — plecos handle green algae and biofilm, SAEs handle BBA ^[4]. Neither species alone controls everything in a planted tank. Photo: Tropical Fish Co warehouse.

What BBA actually is

Black beard algae is a red algae (Audouinella / Compsopogon complex) that appears as dark tufts on driftwood, plant leaves, and filter outlets. It loves moving water and thrives in tanks where CO₂ is unstable or where flow patterns create dead spots.

The biological control options (ranked)

1. Real Siamese algae eater — the only species that actually eats it. Expect 2–4 weeks to clear a visible outbreak.
2. Amano shrimp — will nibble BBA when very hungry; not reliable, but they chew down the early-stage tufts.
3. Everything else on the internet — myth. Bristlenose plecos, otocinclus, ramshorn snails, flying foxes, cherry shrimp: all ignore BBA ^[4].

Chemical control alternative

Excel / liquid carbon (Seachem Flourish Excel, APT Fix) kills BBA on contact when spot-treated with a syringe. Works but kills mosses and vallisneria if overdone. Most aquascapers combine: an SAE for ongoing control + Excel spot-treatment for stubborn patches.

Tank size and stocking

Minimum tank: 120 L for a single SAE. Recommended: 200 L+ for a pair or group.

Stocking guide by tank size:

• 120 L planted — 1 SAE + full community below (tetras, shrimp, corydoras, otocinclus) — the classic single-SAE planted setup
• 180 L planted — 1 SAE + 2 L-number plecos OR a pair of dwarf cichlids — still solo for the SAE, larger community around it
• 250 L+ planted — 5 SAEs + any compatible community — the first tank size where keeping them in a group works

Watch: a mature planted tank with an SAE grazing

Tank mates for a Siamese algae eater

SAEs work well with almost anything peaceful. The rules are:

• No fin-nippers — barbs will nip the SAE's dorsal
• No territorial species — red-tail sharks, blue rams, and adult bettas will fight a settled SAE
• Nothing small enough to eat — fry from livebearers will be picked off

Safe community pairings:

• Schooling tetras — cardinals, embers, harlequin rasboras, neons all work well. The SAE ignores water-column fish.
• Corydoras catfish — different feeding zone (substrate), no conflict.
• Otocinclus — different algae preference, different feeding zone. Excellent partnership.
• Amano shrimp — safe in large enough tanks. Juvenile shrimp may be snacked on.
• Bristlenose pleco — compatible if the tank is 180 L+. Below that, territorial overlap becomes an issue.

When your SAE arrives — our UK delivery protocol

SAEs ship well. Their body size and low stress response mean they tolerate the 14–20 hour overnight courier journey better than smaller, more delicate tetras.

1. Open in a quiet room, lights dim.
2. Float the bag 20 minutes sealed.
3. Drip-acclimate 40 minutes at 1–2 drops per second.
4. Net into the tank.
5. Lights off 2 hours — SAEs need to find their preferred hiding spot before lights come on.
6. No feeding for 24 hours. They'll start grazing on whatever algae is in the tank within 48 hours.

Ready for more?

Looking at the other algae specialists? See our ancistrus pleco guide for the best biological control on green algae, or the otocinclus care guide for the nano-tank glass-cleaner. The amano shrimp care guide covers the invertebrate half of the algae crew.

Shopping for the full planted-tank algae stack? Start at the catfish & plecos hub.