|Synonyms||Ctenogobius candidianus, Rhinogobius taiwanus|
|Distribution||China and Taiwan.|
|Sexual Dimorphism||Dominant males are larger, more colourful, and develop elongated dorsal fins. Mature females will appear fuller bodied, with a dark belly patch when gravid.|
|Maximum Size||10cm (3.9")|
|Temperature||Subtropical: 18-25 deg C (65-77 deg F)|
|Water Parameters||pH: 7.0-7.8, dH: up to 20 degrees. High O2 level essential.|
|Compatibility||Specialist community of current-loving subtropical fish.|
|Lighting||No special requirements|
The Candi River Goby is known from small, cool, gravelly/rocky bottomed, fast-flowing tributaries of the Darchia, Holong, Jongkang, Joshuei, Marlian, Parlian, Shuanshi, Tamshuei, and Tatu Rivers. Although this species was apparently described from Lake Candidius (Sun Moon Lake) and named after such, it has only been found in influent waterways and not in the lake itself. Candi River Gobies have modified pelvic fins which create an area of suction and allow them to cling on to smooth rocks in the swiftest of currents, and these fast-flowing conditions of the natural habitat should be emulated as closely as possible in the home aquarium. Provide a substrate of smooth fine gravel or sand, along with plenty of smooth rocks, creating lots of small nooks and crannies. Highly oxygenated water is essential, so ensure powerful water movement with the use of external canister filtration (water returned via a spraybar) and additional powerheads. Plants can be incorporated into the aquarium, but not all will enjoy the fast flowing conditions. Opt for hardy species such as Java Fern or Anubias sp. anchored to some of the décor, or species that have evolved to thrive in fast flowing waters such as Cryptocoryne balansae. Consistent good water quality is essential to the wellbeing of these fish. Males will chose a preferred territory and defend it against any conspecifics, chasing them away whilst flaring the gills in a remarkable but harmless display. Even the females will show signs of minor territorial aggression from time to time, and may squabble with one another, particularly when gravid. Again, most of this is for show and no physical damage should ensue. These fish are best housed as a good sized mixed-sex colony (ideally with females outnumbering males) in a spacious aquarium, with plenty of visual barriers amongst the décor. In smaller aquaria, house only a single pair; otherwise there will not be enough territory to go around. Tankmates should be small and peaceful and also thrive in cool, fast-flowing water; some of the smaller danionins and barbs are good choices, as are some of the hillstream loach species. This species is not to be trusted with any tiny fish or fry, and do not house with small ornamental shrimps, as these will be eaten! May also be seen on sale as Candidius Goby.
Although these fish will graze upon the natural algae within the aquarium for the small micro-organisms it may contain, the diet must be supplemented with small frozen foods such as vitamin/Spirulina-enriched brineshrimp, bloodworm, white mosquito larvae, daphnia etc. Many specimens will also adapt to taking dried foods such as sinking catfish pellets and algae wafers, although frozen foods tend to be preferred.
This egg-laying species has been bred in the home aquarium, but it is very challenging. It is vital for egg development that water quality is kept extremely high with minimal organic wastes present. Depending on the size/age of the female, up to 200 adhesive eggs will be laid on the walls/roof of a chosen cave; the male fish will then guard them. Unfortunately it seems quite common for the male to eat some of the eggs, particularly if he is a young and inexperienced. For this reason, some aquarists choose to move the eggs into a breeding tank or a breeding net, and use gentle aeration to simulate the male fanning oxygenated water over the eggs. Others choose to move the male fish in with the eggs until they hatch, at which point he is returned to the main tank. A lot of trial and error may be required, as each fish will vary somewhat in temperament and behaviour when breeding. The eggs are very prone to fungussing, so the addition of alder cones can be very beneficial. Depending on water temperature, the eggs should hatch within 9-12 days, at which time the larvae will begin feeding from their large yolk sacs, and due to the sheer size of the sacs they are pretty much immobile at this stage. After several days, the yolk sacs will have been consumed enough for the youngsters to begin moving around. Bacterial infections can occur very easily at this stage, so it is very important to perform small water changes (with water of the same temperature) on a regular basis and ensure the base of the breeding container is free of any detritus. The yolk sacs do not have to have been fully absorbed before the fry start feeding (some will start as early as 2 days after hatching) on baby brineshrimp, moving on to slightly bigger foodstuffs as they grow.