Taxonomy & naming
Rhinogobius lindbergi was described by the Russian zoologist Lev Semyonovich Berg in 1933 from material collected in the Amur River basin. Berg is best remembered for his monumental work on fishes of the USSR, and this species was among the many gobies he catalogued from far-eastern Russian drainages. The Catalog of Fishes — the authority for valid names — places the species in Rhinogobius, a large and taxonomically active genus of Asian river gobies in the family Oxudercidae.
Rhinogobius belongs unambiguously to the true gobies, not to the sleepers or gudgeons. The quickest way to confirm this is the pelvic fins: in the true gobies (Oxudercidae and related families) the pelvic fins are fused along the midline to form a cup-shaped sucker disc, a structure absent in the eleotrids. Despite the name 'goby' being applied loosely to many freshwater fish in the hobby, only species with that fused pelvic disc are true gobies. Rhinogobius lindbergi has it.
The species is commonly called the Amur goby after its native river system. It should not be confused with the many other Rhinogobius species from eastern Asia, several of which have been introduced outside their native range — this species has been recorded as an introduction in Lake Buyr in Mongolia and, remarkably, in the Tigris River drainage of Iran, demonstrating a degree of ecological plasticity unusual for a temperate endemic.
Morphology
Rhinogobius lindbergi is a small, bottom-hugging fish that typically reaches 1–1.5 in standard length in the wild, with a maximum around 2 in; hobby sources cite adults approaching 2–4 in, though wild-caught morphometric data from Iran places most specimens firmly in the 1–1.5 in SL range. The body is elongate and slightly cylindrical, as is typical of the stream-dwelling Rhinogobius, adapted for life on and near the substrate in flowing water.
The preopercular canal carries two terminal pores, a diagnostic character noted in FishBase. As in other Rhinogobius the male is more brightly patterned than the female during breeding condition, with the head and anterior body taking on stronger contrast and the fins becoming more elaborate. The defining structural character — shared across all true gobies — is the fused pelvic disc: the two pelvic fins are united along the inner margin to form a shallow cup that the fish uses to grip the substrate in fast current.
Habitat
The native range of Rhinogobius lindbergi is the Amur River basin, one of the great temperate river systems of northeast Asia, draining parts of northeast China (Manchuria), the Russian Far East, and Korea. The Amur system is cold by aquarium-fish standards — this is a continental temperate zone with cold winters and warm summers — and R. lindbergi is adapted to that seasonality. It lives in swift, well-oxygenated streams and rivers over sandy and stony substrates, the typical habitat of the genus: flowing water with cover among rocks and crevices rather than still, warm water.
The water chemistry is moderately alkaline (pH 7.0–8.0) and cool, with the species tolerating temperatures down to around 39 °F and preferring a range of roughly 50–77 °F. This is emphatically not a tropical fish, and it is sensitive to high temperatures and low dissolved oxygen — the two stressors most likely to kill it in an aquarium. Its introduction into Lake Buyr in Mongolia and the Tigris drainage of Iran suggests it can adapt to a range of still and flowing habitats, but its optimal environment is fast, cold, clean flowing water.
Feeding
Rhinogobius lindbergi is a micro-predator, taking small invertebrates from the substrate and water column in the manner of all Rhinogobius. In the wild its diet consists of aquatic insect larvae, small crustaceans, copepods, and other benthic invertebrates associated with stony stream beds.
In the aquarium it does best on live and frozen meaty foods: bloodworm (frozen or live), brine shrimp, daphnia, cyclops, and similar small items. Like most small gobies it is reluctant to accept dry flake and will lose condition if kept on flake alone; small sinking pellets can supplement the diet but should not be the staple. Offering a variety of live and frozen foods is the single most important factor in keeping these fish in good condition and inducing breeding.
Mating
Rhinogobius lindbergi is a resident freshwater cave-spawner — the breeding strategy shared by most members of the genus and the feature that makes them practical aquarium subjects, in contrast to the amphidromous gobies whose larvae must develop at sea and which cannot complete their life cycle in the home aquarium. Males establish and defend territories centred on a cave or crevice, using the shelter both to rest and to attract females for spawning.
Male courtship in Rhinogobius involves displays at the cave entrance, fin spreading, and intensified colouration. Males are territorial toward one another and will spar, so in a community of these fish each male needs his own cave with adequate line-of-sight breaks between territories. A female in breeding condition will be led or drawn into the cave to spawn. Because the full breeding cycle takes place in fresh water, pairs can and do reproduce in the aquarium when kept in appropriate conditions.
Breeding
Spawning takes place inside the cave or crevice. The female deposits a clutch of adhesive eggs on the roof or walls of the shelter, and after spawning the male blocks or guards the cave entrance — sometimes piling sand across the opening — to protect the eggs. The male then takes sole responsibility for the clutch, guarding and fanning the eggs to keep them oxygenated and free of fungus until they hatch.
Keepers report that once the fry hatch, the male may switch from protective to predatory behaviour toward the young and should be removed, or the cave with its eggs should be moved to a separate rearing tank before hatching. Fry are tiny at hatching and will need infusoria or other microscopic first foods before graduating to newly hatched brine shrimp. A cool, mature, well-filtered tank with caves (inverted flower-pot saucers with a notch cut in the rim, or commercially available cave ornaments), a gentle current, and regular live-food feeding will usually produce spawning attempts in a healthy pair. Water temperature toward the cooler end of the tolerated range (59–68 °F) encourages breeding for this temperate species.
In the aquarium
The Amur goby is a suitable fish for a cool temperate nano aquarium, comparable in care to other cool-water stream gobies such as the Japanese Rhinogobius brunneus rather than to warm-water tropical species. A tank of around 23.5 in provides adequate room for a pair or a small group; a 17.5 in tank can work for a single pair. Filtration should produce a moderate current and keep the water well-oxygenated; inadequate oxygenation and high temperatures are the two most common causes of loss.
The tank should be furnished with sandy or fine-gravel substrate, smooth stones and caves — these are the foci of the fish's territory and spawning activity. Males are territorial with conspecifics, so each fish needs a cave of its own with broken lines of sight. The aquarium must be tightly covered: like most stream gobies, Rhinogobius are capable jumpers and will exit an open tank. This species does not require salt and should be kept in fresh water.
Compatible tankmates are other cool-water fish that will not intimidate or outcompete these small gobies for food: similarly-sized temperate species, dojo loaches at a similar temperature range, or smaller cool-water cyprinids. Avoid tropical community fish that demand 79–82 °F water — such temperatures are stressful or lethal to R. lindbergi. Diet should be varied and meaty, with an emphasis on live and frozen foods.
Conservation
Rhinogobius lindbergi is assessed as Least Concern on the IUCN Red List (assessment completed 11 March 2020), a status consistent with its distribution across the large and relatively intact Amur River system. FishBase records low fishing vulnerability and high population resilience (minimum population doubling time under 15 months), typical of a small, fecund goby.
The Amur basin itself faces ongoing pressures from pollution, agricultural runoff, and dam construction in China and Russia, but the basin is large enough that no immediate threat to the species as a whole is recorded. The documented introductions in Mongolia and Iran are of interest; introductions of stream gobies to new systems can have unpredictable effects on native invertebrate communities. There is no evidence that aquarium trade drives significant collection pressure on this species.