Sucking Loach
Gyrinocheilus aymonieri
Sold young as an algae-eater but grows large and aggressive - research before buying.
| Difficulty | Intermediate |
| Min. Tank Size | 200 L |
| Temperature | 22.0–28.0 °C |
| pH Range | 6.0–8.0 |
| Max Size | 25.0 cm |
| Lifespan | 5-10 years |
| Diet | Herbivore |
| Temperament | Aggressive |
Overview
The Sucking Loach (Gyrinocheilus aymonieri) is sold young as an algae-eater but grows large and aggressive - research before buying. It is a popular choice among Australian aquarists, reaching around 25 cm and living roughly 5-10 years when properly cared for.
This complete guide covers how to keep the Sucking Loach successfully - tank size and setup, water parameters, the best foods (including recommended brands), suitable tank mates, breeding, sexing and the health issues to watch for. It is rated Intermediate to care for.
Natural Habitat & Origin
Loaches come from the streams and floodplains of South and South-East Asia, foraging along the bottom among rocks and roots; many are scaleless, so clean, stable water matters.
Matching the temperature, water chemistry and cover a species evolved with is the simplest route to keeping it healthy and seeing its natural behaviour and colour.
Tank Size & Aquarium Setup
Provide a minimum of 200 litres for the Sucking Loach. Give it a large footprint with sight-breaks and cover to reduce territorial aggression.
Live plants, driftwood and shaded retreats give security and show off the fish's colours against a natural backdrop.
Always add fish only to a fully cycled, mature tank with stable biological filtration. Match filtration generously to the fish's size and waste output.
Water Parameters
Keep the Sucking Loach in stable water at 22-28 °C with a pH of 6.0-8.0. It adapts to a moderate range, so stability matters more than an exact figure.
Test regularly: ammonia and nitrite must read zero, and nitrate should be kept low with routine partial water changes. Always dechlorinate and temperature-match new water, because sudden swings cause far more illness than water that is stable but slightly imperfect.
Diet & Feeding
The Sucking Loach is a herbivore and grazer that needs a plant- and algae-based diet rather than meaty foods it cannot fully digest.
In Australia, good options include Hikari Algae Wafers, API Algae Rounds and Dymax Spirulina wafers, plus blanched vegetables. Feed small amounts once or twice a day (only what is cleared in a minute or two), vary the diet for the best colour and health, and avoid overfeeding, which is the leading cause of poor water quality.
Temperament & Tank Mates
The Sucking Loach is aggressive and is best kept alone or only with very carefully chosen, equally robust tank mates in a large tank. Avoid keeping it with small or timid species it will bully or eat.
Breeding
The Sucking Loach is rarely or not bred in the home aquarium; most stock is commercially farmed or wild-collected, and home breeding is considered very difficult.
Even if you are not planning to breed it, recognising this behaviour helps you understand what you are seeing and respond well - for example by adding cover for fry or giving a guarding pair extra space.
How to Tell Males from Females
Most loaches are hard to sex; females are often rounder-bodied when mature, but reliable differences are subtle.
Common Health Problems
Scaleless and fine-scaled fish like this react badly to poor water and to copper-based or full-dose medications, so treat at half strength. They are also among the first to show ich. Quarantine new arrivals for 2-4 weeks and watch daily for early signs such as loss of appetite, unusual hiding, clamped fins or laboured breathing - caught early, most issues are very treatable.
Prevention beats cure: keep water pristine, avoid overstocking and overfeeding, quarantine new arrivals, and act at the first sign of trouble.
Is the Sucking Loach Right for You?
The Sucking Loach suits keepers with some experience and a stable, mature, appropriately sized tank, as long as you can provide at least 200 litres, water at 22-28 °C and pH 6.0-8.0, the right diet and suitable tank mates.
Meet those needs and the Sucking Loach will reward you for around 5-10 years. Use our free aquarium calculators to plan your setup, and explore our other fish, plant and disease guides to build a thriving aquarium.
