Dwarf Spotted Rasbora (Rasbora Maculata)

A crimson-flecked jewel of blackwater swamps, scarcely longer than a grain of rice.

The Dwarf Spotted Rasbora (Rasbora maculata) is a tiny, peaceful schooling fish for mature soft-water nano aquariums, best kept in groups of eight or more.

• Water conditions: The Dwarf Spotted Rasbora comes from soft, acidic blackwater habitats in Southeast Asia, so it performs best in a mature aquarium with stable parameters. Aim for a temperature of 23–26°C (73–79°F), pH around 5.0–7.0 with 5.5–6.5 ideal, and a hardness of 1–5 dGH. Keep nitrate low and avoid sudden swings in pH, temperature or hardness. If your tap water is hard or alkaline, mix it with RO water and use tannin-rich botanicals such as Indian almond leaves or alder cones. Gentle filtration and good oxygenation are useful, but strong current should be avoided because these tiny fish tire easily in brisk flow.
• Tank size and aquascaping: A group is best housed in an aquarium of at least 45 cm (around 10 gallons) with a soft, fine substrate, dim lighting and plenty of cover. Floating plants, mosses, fine-leaved stems, leaf litter and small botanicals create the shaded, naturalistic environment this species appreciates. Leave some open midwater space for schooling behaviour, but keep the tank well structured so subordinate fish can retreat if needed. A closely fitting lid helps maintain humidity and prevents accidental jumping, while a gentle air-driven sponge filter or well-baffled internal filter suits the calm flow these rasboras prefer.
• Suitable tank mates: Choose only small, peaceful species that will not outcompete or intimidate the Dwarf Spotted Rasbora. Good companions include other micro rasboras, small peaceful tetras, pygmy corydoras, Otocinclus, small loaches and peaceful snails. Adult cherry shrimp are usually safe, though very small shrimplets and fry may be eaten. Avoid large, boisterous or predatory fish, fin-nippers, and species that feed aggressively at the surface. Because these rasboras are shy, dither fish of a similar size can increase confidence, but the group itself should always be the main focus. Quarantine new tank mates where possible to protect this sensitive little fish from introduced disease.
• Feeding habits: The Dwarf Spotted Rasbora is a micropredator with a small mouth, so it needs foods sized for tiny fish. Offer live or frozen daphnia, moina, cyclops, baby brine shrimp, microworms and grindal worms, alongside a finely crushed micro flake or micro pellet. Feed two or three very small portions daily, giving only what the group can clear in a few minutes. Variety is important for condition and colour, and live foods are especially valuable. Avoid large pellets, coarse flakes and overfeeding, which can foul the water and cause health problems. Watch that slower individuals receive food, as the group can be timid when feeding.
• Care requirements: This is a sensitive nano fish that is not suitable for a newly cycled or unstable aquarium. Keep the tank mature, lightly stocked and consistently maintained with small regular water changes of around 10–20% weekly. Siphon debris gently, rinse filter media only in tank water, and avoid drastic cleaning that disrupts the biological filter. Maximum adult size is only around 2.5 cm (1 inch), so even a small tank can become overloaded if stocking is too heavy. Maintain stable temperature and low nitrate, observe the group daily, and act quickly if you see clamped fins, laboured breathing, loss of colour or reduced feeding.
• Acclimation and health: Drip acclimation is strongly recommended over 45–60 minutes, especially when moving the fish between different pH or hardness levels. Keep the aquarium lights off during introduction and avoid netting the fish more than necessary. A short quarantine period in a quiet, established observation tank allows you to check for signs of stress or disease before adding the rasboras to a community display. Do not use prophylactic medications without cause, and never rush the acclimation process. Once settled, a stable routine, gentle handling and a calm environment are the best safeguards for long-term health.
• Behaviour and group size: Dwarf Spotted Rasboras are schooling fish that should be kept in groups of at least eight to ten, with larger groups producing more natural behaviour and greater confidence. In a suitably sized group, males may show brighter colour and mild sparring, but aggression is rarely serious. These fish are shy and can spend much of the day among plants and leaf litter, so provide plenty of cover and avoid noisy, high-traffic positions. A settled group makes a beautiful, active addition to a dedicated blackwater nano setup and is far more rewarding than keeping only one or two specimens.