Overview
The Gold Spotted Dwarf Danio, scientifically known as Boraras merah and frequently traded as the Phoenix Rasbora, is a stunning micro-fish belonging to the family Cyprinidae. Due to its diminutive size and striking red and gold markings, it has become a staple in the nano aquarium hobby. They are peaceful, schooling fish that thrive in environments that mimic their natural blackwater habitats.
Distribution and Habitat
This species is endemic to southern Borneo in Indonesia. They are exclusively found in highly acidic blackwater streams and peat swamp forests. These waters are typically stained dark brown with tannins released by decaying organic matter, such as fallen leaves and branches. The water is extremely soft, with a very low pH and minimal mineral content, shaded by dense jungle canopies.
Description of Gold Spotted Dwarf Danio
Body shape:
The Gold Spotted Dwarf Danio features a slender, elongated, and highly streamlined body typical of micro-rasboras and danios. Their diminutive profile allows them to navigate easily through dense vegetation and leaf litter.
Color:
The base coloration is somewhat translucent, overlaid with vibrant, rusty red to fiery orange hues, particularly on the males. Their defining feature is a prominent dark, oval-shaped blotch on the flanks, which is often encircled by a bright, glowing gold or fiery orange ring.
Barbels:
Like many species in the Boraras genus, they lack barbels around the mouth.
Snout:
The snout is short, somewhat pointed, and features a small, terminally positioned mouth perfectly adapted for hunting tiny micro-organisms in the water column.
Eyes:
The eyes are relatively large compared to the overall size of the head, often exhibiting a slight reddish or golden iridescence along the upper rim.
Fins:
The dorsal and anal fins are largely translucent but are heavily marked with vibrant red patches and distinct black leading edges. The pelvic fins may also show hints of red.
The Tail:
The caudal (tail) fin is deeply forked and mostly clear, though it often features small, bright red or orange accents at the base of the lobes.
Temper
This is an exceptionally peaceful species. Due to their tiny size, they are easily intimidated and can become stressed or outcompeted for food if housed with larger, overly boisterous, or aggressive tank mates.
Sociality
Gold Spotted Dwarf Danios are highly gregarious and must be kept in groups. A minimum school of 8 to 10 individuals is highly recommended, though larger groups of 15 or more will result in much bolder behavior, tighter schooling, and far more intense coloration as males display to one another.
Activity
They are active, diurnal swimmers that typically occupy the middle to upper levels of the aquarium. They spend much of their day exploring plant leaves and darting through the water column in search of tiny food particles.
Keeping and Caring for Gold Spotted Dwarf Danio
Tank size:
Despite their active nature, their tiny size means they do not require a massive aquarium. A 5-gallon (20-liter) tank is the absolute minimum for a small school, though a 10-gallon (40-liter) setup is highly preferred to ensure stable water parameters and provide ample swimming space.
Water Parameters:
Temperature
They thrive in tropical temperatures ranging from 20 to 28°C (68-82°F). Stability is more important than hitting a specific number within this range.
pH
Originating from peat swamps, they require acidic water to truly thrive and show their best colors. A pH range of 4.0 to 6.5 is ideal.
Hardness
The water should be very soft, ideally between 1 and 5 dGH.
Ammonia, Nitrite, Nitrate
Like all fish, they require 0 ppm of Ammonia and Nitrite. Nitrates should be kept as low as possible, strictly below 20 ppm, through regular maintenance and live plants.
Lighting
Dim to moderate lighting is preferred. Bright lighting can wash out their colors and cause stress unless heavily diffused by floating plants.
Water flow
They originate from sluggish waters, so filtration should be gentle. A sponge filter is highly recommended to provide adequate filtration without creating a strong current that would exhaust them.
Decorations and Plants
The ideal setup heavily features live plants, including floating varieties like Salvinia or Frogbit to dim the light. Substrate should be dark, and the addition of driftwood, botanical pods, and dried leaf litter (such as Indian Almond leaves) is essential to release tannins, lower the pH, and mimic their natural blackwater habitat.
Diet
In the wild, they are micropredators feeding on tiny insects, worms, and zooplankton. In the aquarium, their tiny mouths require appropriately sized foods. They will accept crushed, high-quality flakes or micro-pellets, but their diet should be heavily supplemented with live or frozen foods such as baby brine shrimp, Daphnia, micro-worms, and cyclops.
Some Feeding Tips
Because of their small stomachs, it is best to feed them two to three small meals a day rather than one large one. Ensure the food is small enough to fit in their mouths to prevent malnutrition.
Breeding
Breeding the Gold Spotted Dwarf Danio is possible and often happens naturally in mature, heavily planted tanks. They are continuous egg-scatterers that provide no parental care and will eat their own eggs if given the chance. To maximize fry survival, set up a dedicated, dimly lit breeding tank with very soft, acidic water and a bottom covered in Java moss or a spawning mop. Once eggs are laid, remove the adults. The fry are incredibly tiny and will require infusoria or paramecium for the first few days before graduating to newly hatched brine shrimp.
Conclusion
The Gold Spotted Dwarf Danio is a gem of the nano aquarium world. While they require a bit of attention to water parameters and diet sizing, their peaceful nature and stunning fiery colors make them an incredibly rewarding species for aquarists looking to create a vibrant, natural blackwater biotope.
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