Tetra Species Guide: Neon, Cardinal, and More for UK Tanks

What Is the Neon Tetras: The UK’s Most Popular Tropical Fish?

Neon tetras (Paracheirodon innesi) are arguably the most recognised tropical fish in the world and a staple of UK aquarium shops. Their brilliant blue and red horizontal stripe makes a stunning display when kept in a school of ten or more. Neons reach 3-4 centimetres and suit tanks from 60 litres upward, though larger tanks allow bigger schools and more impressive displays.

Care requirements include soft to moderately hard water (GH 2-10), slightly acidic to neutral pH (6.0-7.0), and temperatures of 20-26 degrees Celsius. Neons are less demanding about warmth than many tropical species and can tolerate the cooler end of tropical ranges. This makes them compatible with species that prefer slightly cooler water, though a heater is still essential in UK homes. See our aquarium heater guide for temperature management.

The main vulnerability of neon tetras is neon tetra disease (NTD), a parasitic infection caused by Pleistophora hyphessobryconis that is incurable and eventually fatal. Symptoms include loss of colour, erratic swimming, cysts on the body, and wasting. Quarantine and humane euthanasia of affected fish is the only option. Buying from reputable UK suppliers and quarantining new fish reduces the risk. Our fish health guide covers disease identification.

What Are the Cardinal Tetras, Rummy-Nose, and Other Popular Species?

Cardinal tetras (Paracheirodon axelrodi) are often confused with neons but display a red stripe that extends the full length of the body (neons’ red covers only the rear half). Cardinals are slightly larger (4-5 cm), prefer warmer water (24-28 degrees Celsius), and are generally considered more colourful. They need softer, more acidic water than neons (pH 5.5-7.0) and are slightly more sensitive. UK prices range from 2-4 pounds each.

Rummy-nose tetras (Hemigrammus rhodostomus and related species) are prized by experienced fishkeepers for their tight schooling behaviour and the vivid red nose that serves as a health indicator: a bright red nose indicates optimal water quality, while a pale nose signals stress or poor conditions. They need warm water (24-28 degrees Celsius) and consistent conditions. Their schooling display in a well-planted tank is among the most attractive sights in the freshwater hobby.

Ember tetras (Hyphessobrycon amandae) are tiny (2 cm) orange-red fish perfect for nano tanks from 30 litres. Black phantom tetras, serpae tetras, and glowlight tetras offer variety in colour and form. Larger species like Congo tetras (8-10 cm) and Buenos Aires tetras (6-8 cm) suit bigger tanks of 150+ litres. Each species has specific requirements; check individual care sheets before purchasing. Our community fish guide covers compatible combinations.

How Should You Schoole Requirements and Tank Setup?

Tetras are obligate schooling fish that must be kept in groups. A minimum of six is the absolute baseline, but ten or more is strongly recommended for natural behaviour and visual impact. In groups below six, tetras become stressed, display muted colours, hide excessively, and may develop health problems. The schooling behaviour itself, with the group moving in coordinated formations, only emerges in adequate numbers.

Tank setup should include open swimming space in the centre and front, with planted areas along the back and sides. Tetras use the planted areas for security and rest, and the open areas for schooling displays. Floating plants are beneficial as most tetra species come from shaded forest streams and prefer subdued lighting. Dark substrate enhances tetra colours significantly; a black sand or gravel substrate makes neons and cardinals appear much more vivid.

Filtration should provide clean water with gentle to moderate flow. Strong currents exhaust small tetras and disrupt schooling patterns. A sponge filter or HOB filter with adjustable flow suits most tetra setups. The tank must be fully cycled before adding tetras; they are sensitive to ammonia and nitrite spikes. See our tank cycling guide for the complete process and our lighting guide for plant-friendly setups that suit tetras.

How Should You Feed Tetras: Small Mouths, Specific Needs?

Most tetras have small mouths relative to their body size, which means standard tropical flakes may need to be crushed or replaced with micro-pellets. High-quality micro-pellets or nano fish food (such as Hikari Micro Pellets, Fluval Bug Bites Small Fish, or Dennerle Nano Gran) provide appropriately sized pieces with balanced nutrition. Feed once or twice daily in amounts consumed within 2 minutes.

Frozen foods are enthusiastically consumed and provide essential variety. Daphnia, baby brine shrimp, cyclops, and bloodworm (chopped for smaller species) are all excellent supplements offered 2-3 times weekly. Live foods, when available, trigger the most enthusiastic feeding response and provide superior nutrition. UK aquatic shops occasionally stock live daphnia and brine shrimp, and cultures can be maintained at home.

Colour-enhancing foods containing astaxanthin and carotenoids intensify the red and orange pigments in tetra species. These are available as dedicated colour-enhancing flakes or pellets from most UK aquatic retailers. While not essential, they can noticeably improve the vibrancy of neon, cardinal, and ember tetras. A varied diet naturally provides some colour-enhancing nutrients without dedicated products. See our feeding schedule guide for portion control and timing.

What Is the Tetra Tankmates and Community Compatibility?

Tetras are among the most compatible community fish available. Ideal tankmates include corydoras catfish (which occupy the bottom level), small peaceful barbs (cherry barbs, harlequin rasboras), small gouramis (honey gouramis, sparkling gouramis), and invertebrates (shrimp, snails). The combination of tetras in the mid-water, corydoras on the bottom, and perhaps a small surface-dweller creates a visually engaging multi-level community.

Avoid housing tetras with large or aggressive species that may eat or bully them. Cichlids (except very small species like Mikrogeophagus ramirezi), large barbs (tiger barbs are notorious fin-nippers), and predatory fish are unsuitable. Some tetra species can be nippy themselves; serpae tetras and black skirt tetras are known for fin-nipping in small groups, so keep them in larger schools (12+) to contain the behaviour within the group.

When combining multiple tetra species, ensure similar water parameter requirements and avoid mixing species that look too similar, which can cause confusion and failed schooling. A classic UK community setup might include a school of 10 neon tetras, a school of 8 ember tetras, 6 corydoras, and a pair of honey gouramis in a 120-litre planted tank. This creates a beautiful, harmonious display using species readily available from UK shops. Check our tank setup guide for stocking calculations.