Palauan Riffle Dwarf Goby (Stiphodon Pelewensis)

Clings to rushing riffles, a tiny Palauan goby built for current.

The Palauan Riffle Dwarf Goby (Stiphodon pelewensis) is a peaceful algae-grazing goby for mature, high-flow freshwater tanks with smooth stones and superb oxygen.

• Water conditions: The Palauan Riffle Dwarf Goby is best suited to a stable, well-oxygenated freshwater aquarium that mimics a fast-flowing forest stream. Aim for a temperature of 22–26°C (71–79°F), pH around 6.8–7.8, and moderate general hardness of roughly 5–12 dGH. The key requirement is high dissolved oxygen and strong, continuous water movement; use a canister filter outlet, spray bar, powerhead, or dedicated stream pump to create riffle-like flow, ideally turning the tank volume over 10–15 times per hour. Keep ammonia and nitrite at zero and nitrate low, ideally below 20 ppm, through regular partial water changes. Avoid sudden swings in temperature, pH, or hardness. A mature tank with visible biofilm, algae films on smooth cobbles, and clean water is far more important than exact numbers. These gobies are sensitive to low oxygen, accumulated organics, and newly cycled aquariums, so do not add them to an immature setup.
• Suitable tank mates: This dwarf goby is peaceful and does not intentionally harm other fish, but it should not be kept with boisterous, predatory, or food-competing species. Good tank mates include small, peaceful schooling fish such as microrasboras, small rasboras, gentle danios, and other calm stream fish that tolerate flow. Small peaceful loaches and certain non-aggressive bottom dwellers can work in a sufficiently large, well-structured tank, provided they do not outcompete the gobies for algae and biofilm. Avoid large cichlids, aggressive barbs, puffers, crayfish, and any fish large enough to eat the gobies. Adult shrimp and peaceful snails are usually safe. Conspecific behaviour needs care: males can be territorial, especially in small tanks, so keep a single male with two or more females in a larger setup, or use a species-specific arrangement with plenty of smooth stones and visual barriers. Do not overcrowd, and avoid adding them to tanks with fish that aggressively graze the same surfaces.
• Feeding habits: Stiphodon pelewensis is primarily an algae grazer and biofilm feeder, not a typical meat-eating goby. In a mature aquarium it will constantly graze smooth stones, glass, driftwood, and broad plant leaves for algae, diatoms, and micro-organisms. This natural grazing should be supplemented with spirulina-based sinking wafers, algae tabs, Repashy-style gel foods, nori, and blanched vegetables such as zucchini, cucumber, spinach, or broccoli. Small amounts of frozen or live foods, including baby brine shrimp and daphnia, can be offered occasionally, but high-protein diets should not form the staple. Feed little and often, and remove uneaten food promptly to protect water quality. Newly imported specimens are often thin and may ignore prepared foods at first, so a mature tank with abundant biofilm is critical. Never rely on scavenging alone; offer algae-rich foods several times a week and observe that the fish is actively grazing and maintaining body weight.
• Care requirements and tank setup: Provide a tank of at least 60 cm in length, with a larger footprint for a group. Use a soft sand or fine rounded gravel substrate, smooth river cobbles, driftwood, and open grazing surfaces. Avoid sharp rocks and coarse gravel that can damage the goby’s delicate skin and mouth. Strong flow, high oxygen, and a tight-fitting lid are essential because these gobies can cling to glass and may climb near the water line. Lighting should be moderate enough to encourage algae growth without overheating the water. Maintain a strict maintenance routine with regular partial water changes, filter cleaning, and good surface agitation. Drip-acclimatise new arrivals slowly, quarantine where possible, and avoid sudden changes in salinity or temperature. This species is amphidromous: adults live and breed in freshwater, but larvae require a marine or brackish phase, so captive breeding is not expected in a normal freshwater aquarium. They are peaceful but sensitive, and are best kept by aquarists who can provide stable water, strong current, and a continuous natural grazing surface.
• Behaviour and ideal aquarium maturity: Palauan Riffle Dwarf Gobies are active, curious bottom-dwellers that spend much of the day clinging to stones and grazing. They are not aggressive toward unrelated fish, but males may posture or chase one another when space is limited. Provide plenty of smooth stones and visual breaks to reduce territorial pressure. Because they feed continuously on biofilm, the aquarium should be running for several months before adding them, with stable filtration and a healthy algal film on hardscape. Avoid keeping them in bare, sterile tanks or with powerful wavemakers that create turbulent, unsafe conditions; the flow should be strong but not chaotic. Observe feeding and body condition closely, especially during the first few weeks, and act quickly if a specimen becomes thin or reclusive.
• Summary of key needs: High oxygen and strong flow, stable freshwater parameters, mature biofilm and algae, smooth rounded hardscape, peaceful tank mates, and a diet based on spirulina, algae wafers, and blanched vegetables. Avoid new tanks, low oxygen, aggressive tank mates, and high-protein staple foods. With the right riffle-style setup, Stiphodon pelewensis is a fascinating and peaceful nano-stream goby that rewards careful acclimation and attentive feeding.