Matt Clarke takes a look at one of the few species of freshwater bumblebee goby.
Common name: Freshwater bumblebee goby
Scientific name: Brachygobius xanthomelas Herre, 1937
Origin: Cambodia, Indonesia, Malaysia and Singapore.
Size: Around 2cm/0.75"
Diet: Probably zooplanktivorous, so offer small frozen foods, such as brineshrimp and Daphnia.
Reader John Robertson has kept this species long term. He says they are choosy about foods, but relished newly hatched brineshrimp but only picked at other foods, including frozen Cyclops, lobster eggs and Daphnia.
Water: This is one of a couple of species of bumblebee goby to occur only in freshwater, so there's no need to add salt. John kept his in softwater (50% rainwater) at about 3GH, pH 6.0 and a temperature of 80F. His fish have spawned once, so the conditions do seem appropriate.
Aquarium: Little is known about the habitat this species come from, so what the aquarium should look like is anyone's guess. I'd go for a smallish tank with a soft, sandy substrate and lots of twig like branches and bogwood. It should mix well with most small, placid species. It would be wise not to mix this with anything too boisterous, as it's not a particularly bold fish and could miss out on food.
John's fish were kept as a group of nine in a 12" x 8" x 8" tank, which was bare apart from some PVC tubes and flower pots for shelter, pebbles and oak leaves.
Identification: The bumblebee gobies are quite complicated to distinguish from each other. It's very difficult to accurately confirm the identity of some species without knowing the collection locality of counting their scales. Given their tiny size, counting scales on these fish is really only possible with a preserved specimen and a microscope.
These were imported as B. xanthomelas, but there is another Brachygobius that can be confused with this species - the similar looking B. kabiliensis, which also reaches a size of 2cm or so. B. xanthomelas should have 26-27 scales, while B. kabiliensis should have 22-23 in the lateral line series. Unfortunately, I wasn't able to count the scales on these fish from the high resolution photographs, but these do resemble fish identified as xanthomelas that I've seen before. According to PFK website contribtor Dr Heok Hee Ng, xanthomelas also usually has a broken first anal stripe, which is seen on these specimens.
Breeding: John Robertson saw eggs from his fish, but did not manage to rear any fry. Says John: "In general, the fish were rather drab, the base colour being rather washed out. But at times they became much more yellow, contrasting with the black bands.
"In August they spawned and I could see the male protecting the eggs in a narrow (10mm diameter) tube. He kept rubbing his body against them. I expected the fry would be eaten by the other fish, so I tried to move the male and the eggs to another tank.
"Unfortunately, the male was too fast for me and when he fled I couldn't identify him amongst the others. After 24-hours he had not returned to his brood so I removed the eggs anyway. Unfortunately, none hatched and they didn't spawn again."
Unusually, John keeps his in a tank with neither filtration or aeration, relying on regular partial water changes to keep water conditions in check.
Availability: This species only turns up sporadically, and it's rarely offered under its real name as there were. We spotted these on sale at Maidenhead Aquatics @ Peterborough.
Price: £1.50
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