Red Scat (Scatophagus argus) — 8-10cm

Overview

The Red Scat (Scatophagus argus) is a hardy, active brackish-water schooling fish with striking red coloration and a bold personality. Native to Indo-Pacific coastal waters, estuaries, mangroves, and brackish river mouths from South and Southeast Asia to northern Australia, this species inhabits environments where freshwater and marine systems meet. Reaching an impressive 35cm in adulthood, the Red Scat requires a minimum tank of 450 litres, brackish water conditions (with increasing salinity as the fish matures), and careful planning for long-term housing. Available to buy tropical fish online uk from Tropical Fish Co, this fascinating species brings specialist appeal and constant activity to large brackish aquarium systems.

Appearance

Adult Red Scats reach approximately 35cm in length, displaying a deep-bodied, laterally compressed shape typical of Scatophagidae. The species is characterized by striking red-orange coloration with distinctive dark spots or markings across the body and fins. Juveniles typically show more pronounced spotting, while adults may develop more intense red coloration. The species has prominent dorsal and anal fins with spiny rays, creating an impressive silhouette. Coloration intensity varies with diet, water quality, and stress levels. The species' bold appearance and active swimming style make it a centerpiece fish in appropriately sized brackish aquariums.

Natural Habitat

This species inhabits Indo-Pacific coastal waters, estuaries, mangroves, and brackish river mouths from South and Southeast Asia to northern Australia. In the wild, Red Scats form schools in areas where freshwater rivers meet the sea, tolerating a wide range of salinities. Juveniles are often found in lower-salinity brackish water, while adults may venture into full marine conditions. The species grazes on algae, detritus, and plant matter in nutrient-rich estuarine environments. The water in these habitats varies from nearly freshwater to full marine salinity, with temperatures ranging from 22-30°C and pH from neutral to alkaline.

Aquarium Setup

A minimum tank size of 450 litres is essential for keeping Red Scats, providing adequate space for a small school and accommodating their large adult size. Structure the aquarium with smooth rocks, driftwood, and very hardy plants or artificial alternatives (as Scats will graze on and damage soft plants). Use a sandy or fine gravel substrate tolerant of salt addition. Invest in powerful filtration rated for at least double your aquarium volume—Scats produce substantial waste and require excellent water quality. Add marine salt to create brackish conditions, starting with low salinity (specific gravity 1.005-1.010) for juveniles and gradually increasing to higher brackish or marine levels (1.015-1.020+) as fish mature. Strong water circulation and excellent oxygenation are essential.

Water Parameters

This species requires brackish to marine water with a gradual increase in salinity as fish mature. Target pH between 7.0 and 8.5, with temperatures stable between 22-30°C. Salinity should start at low brackish levels (specific gravity 1.005-1.010) for juveniles, gradually increasing to higher brackish or full marine levels (1.015-1.025) as fish grow—research suggests adults do best in higher salinity long-term. Use marine salt mix (not aquarium salt) to achieve appropriate salinity. Perform large weekly water changes of 30-40% using pre-mixed, temperature-matched brackish water. Test salinity using a refractometer or hydrometer, and test other parameters regularly using liquid test kits. The species' changing salinity requirements make long-term planning essential.

Feeding

Scatophagus argus is an omnivore with a strong plant component to its diet. Offer a varied omnivorous diet with substantial vegetable matter: algae wafers, spirulina-based foods, blanched vegetables (spinach, courgette, peas, lettuce), and quality sinking pellets. Supplement with occasional frozen or live foods such as brine shrimp, mysis shrimp, or chopped shellfish to provide protein. Feed two to three times daily, ensuring generous portions of plant matter to satisfy the species' constant grazing behavior. Scats are enthusiastic eaters and will beg for food, but avoid overfeeding as this contributes to water quality degradation. The species' name derives from "Scato-phagus" (dung-eater), referring to its scavenging feeding habits in the wild.

Behaviour

This species displays semi-aggressive, highly active schooling behavior. Red Scats are constantly on the move, swimming energetically throughout all levels of the aquarium. The species is bold, alert, and interactive, often begging for food at the tank glass. Scats feel most secure when kept in groups of at least 3-5 individuals—lone Scats may become stressed or aggressive. The species can display territorial behavior during feeding or in cramped conditions, though aggression is generally manageable in appropriately sized aquariums. Activity levels are high throughout the day, creating constant movement and visual interest.

Tank Mates

Compatible tank mates are limited to other robust brackish fish of similar size that can tolerate increasing salinity as the Scats mature. Suitable options include Monos (Monodactylus species), Archers (Toxotes species), other Scats of similar size, and large brackish gobies. Choose active, confident species that share similar water parameter requirements. Avoid housing with small fish that can be bullied or eaten, slow-moving fish with long fins, freshwater-only delicate species (which cannot tolerate salt), highly aggressive territorial fish, or very small invertebrates such as shrimp and snails. The species' changing salinity requirements and large adult size significantly limit long-term tankmate options.

Breeding

Breeding Red Scats is uncommon in home aquariums and typically requires large groups, excellent water quality, and appropriate salinity conditions that replicate estuarine spawning triggers. Larvae are difficult to raise and may require specialized foods and conditions. Sexual dimorphism is subtle, and most aquarists do not attempt breeding. Most specimens available in the trade are wild-caught or commercially bred in specialist facilities. Aquarists interested in breeding should research specialist brackish-water fish breeding techniques.

Why Buy from Tropical Fish Co

At Tropical Fish Co, we specialize in unusual and specialist fish, including brackish-water species like the Red Scat. Our fish are carefully sourced, quarantined, and conditioned to ensure they arrive in excellent health, ready to thrive in your large brackish aquarium. We provide expert guidance on salinity requirements, long-term planning, and tankmate selection to help you succeed with these striking and active fish. With reliable UK delivery and a commitment to quality, we're your trusted source for brackish fish for sale uk and specialist exotic fish for sale uk.