Description
MacCulloch’s rainbowfish (Melanotaenia maccullochi)
Overview
Melanotaenia maccullochi, commonly known as the dwarf rainbowfish or MacCulloch’s rainbowfish, is a small, vibrant freshwater fish from the Melanotaeniidae family, native to northern Australia and southern Papua New Guinea. Found in diverse habitats like clear streams, turbid ponds, and grassy swamps with dense vegetation, it displays horizontal dark stripes and variable fin colours (red, yellow, or orange) depending on locality. Growing to 7 cm, males are more colourful with longer dorsal and anal fins, while females are deeper-bodied and duller. Its peaceful, adaptable nature and small size make it ideal for planted community tanks, though fry rearing can be challenging. Most aquarium specimens are captive-bred due to its Least Concern status but localized habitat threats.
Care Requirements
Tank Size:
Minimum 55L for a group of 6–8; 113L or larger preferred for shoaling and activity. Base dimensions of at least 60 x 30 cm recommended.
Water Parameters:
- Temperature: 22–28°C; optimal 27–29°C for breeding.
- pH: 6.5–8.0 (neutral to slightly alkaline; adaptable to 5.5–7.5 in some habitats).
- Hardness: 5–15 dGH (soft to moderately hard).
- Ammonia/Nitrite: 0 ppm.
- Nitrate: <30 ppm (ideally <15 ppm to prevent stress).
- Substrate: Fine sand or gravel; dark substrates enhance colouration.
- Décor: Dense plants (e.g., Java moss, Vallisneria, Anubias) and floating plants (e.g., hornwort) for cover. Add driftwood, logs, or smooth rocks to mimic natural habitats with ample swimming space.
- Filtration: Gentle to moderate flow (4–5x tank volume/hour) using sponge or hang-on-back filters for oxygenation without strong currents.
- Lighting: Moderate; floating plants provide shade to reduce skittishness.
- Other: Tight-fitting lid essential, as they are prone to jumping. Avoid CO2 injection to prevent pH swings.
Maintenance
- Water Changes: 20–25% weekly with dechlorinated water matching tank parameters to maintain stability, as they are sensitive to nitrate buildup.
- Tank Cleaning: Siphon uneaten food and debris; lightly vacuum substrate to preserve beneficial bacteria.
- Testing: Weekly checks for pH, hardness, ammonia, nitrite, and nitrate using a reliable test kit to avoid fluctuations.
- Equipment Check: Ensure filters provide gentle flow, heaters maintain stable temperatures, and lid is secure to prevent escapes.
Diet
- Type: Omnivorous; feeds on small invertebrates, algae, and plant matter in the wild.
- Foods:
- Dry: High-quality flakes or micro-pellets (e.g., Fluval Bug Bites, Hikari Micro Pellets) as a staple.
- Live/Frozen: Brine shrimp, daphnia, bloodworms, cyclops (2–3 times weekly to enhance colour).
- Plant-Based: Spirulina flakes, blanched vegetables (e.g., spinach, zucchini) for digestion.
- Feeding: Small portions 2–3 times daily, consumed within 1–2 minutes to prevent overfeeding.
- Notes: Varied diet with live foods promotes vibrant colours, especially in males. They feed at mid-to-surface levels; avoid sinking foods for fry.
Behaviour and Compatibility
- Temperament: Peaceful but skittish; active swimmers that thrive in groups.
- Social Behaviour: Shoaling species; keep 6–8 or more (1–2 females per male) to reduce stress and encourage male colour displays. Fewer than 6 may lead to shyness or reduced activity.
- Compatible Tankmates:
- Small, peaceful fish: Other rainbowfish (e.g., Melanotaenia praecox), neon tetras, rasboras, danios, dwarf cichlids.
- Bottom-dwellers: Corydoras catfish, kuhli loaches, small gobies (e.g., Pseudomugil gertrudae).
- Incompatible: Aggressive or fin-nipping fish (e.g., tiger barbs, large cichlids), slow-moving or long-finned fish (e.g., bettas, guppies), or species requiring vastly different water parameters. Avoid mixing with other rainbowfish variants to prevent hybridization.
- Notes: Dense plants and open swimming areas reduce skittishness and enhance displays. Males show best colours in groups with conspecifics.
Breeding Behaviour
Breeding Type: Egg scatterers; spawn daily in small batches, attaching eggs to plants or spawning mops via adhesive threads.
Picture for illustrative purposes only. Either come in store to view available stock or request pictures to be sent to you.
Please Note: Due to variations within species resulting from age, region, sex, etc., the actual livestock may not look identical to the image. Approximate size range may also vary between individual specimens.
