Can Achara Catfish and Freshwater Harlequin Shrimp (Sulawesi) Live Together?

Achara Catfish is a moderately assertive species (6/10), while Freshwater Harlequin Shrimp (Sulawesi) is peaceful (0/10). This notable difference means Achara Catfish may occasionally assert dominance over Freshwater Harlequin Shrimp (Sulawesi).

Large aggression gap (6 points) between Achara Catfish and Freshwater Harlequin Shrimp (Sulawesi) increases stress risk for the more peaceful fish.

Achara Catfish and Freshwater Harlequin Shrimp (Sulawesi) both frequent the Bottom (Substrate) region of the setup. This overlap can increase competition for space, so providing ample room and cover is important to keep both species comfortable.

There is a critical concern: the Piscivore (Eats small/nano fish) behaviour of one fish directly conflicts with the Nano / Bite-sized (Predation Risk) trait of the other — piscivorous fish will prey on nano-sized tank mates..

Additional behavioural considerations to keep in mind: Shrimp eaters may also prey on very small nano fish.

Worth noting: Achara Catfish is nocturnal and will be most active after lights-out, naturally reducing daytime encounters.

The safe temperature window for both species falls between 26°C and 28°C. Aim for the midpoint of this range (around 27.0°C) for optimal comfort.

Both fish can tolerate a pH between 7.5 and 7.5. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 4–8 dGH. Regular testing will ensure conditions stay within this range.

To house Achara Catfish and Freshwater Harlequin Shrimp (Sulawesi) together, plan for an aquarium of at least 1500 litres with a minimum length of 240 cm. This recommendation combines the stricter species minimums with a community-load allowance so the pairing has realistic long-term space and filtration headroom.

Providing a mix of open swimming space and sheltered areas with rocks, driftwood, or plants will keep both species comfortable and allow natural behaviour.

Specific environmental needs for this combination include: Sand (Sifters), Smooth Gravel (Sensitive Barbels), Driftwood (Digestion/Hiding), Established Algae (Otocinclus). Meeting these requirements will help both species thrive.

Both species do well with moderate (standard) water movement, so a standard filtration setup rated for the tank volume should suffice.

Feeding time deserves special attention with this pairing. Achara Catfish is a known shrimp eater and may prey on small invertebrates or nano fish like Freshwater Harlequin Shrimp (Sulawesi).