A Russian fishkeeper has reported a successful spawning of the Clown loach, Chromobotia macracanthus.
Oleg Mihajlov from Ivanovo, Russia, bred his Clown loaches last month and currently has hundreds of five-week old fry which have now started to take on adult colouration.
However, unlike previously documented spawnings, such as the recent unsuccessful spawning of the Clown loach by British fishkeeper Colin Dunlop (See British fishkeeper spawns Clown loach, News, October 22, 2007), Oleg bred his fish completely artificially.
Mihajlov, a professional fish breeder and ichthyologist, used two injections of a pituitary extract from the Bream, Abramis brama, spaced 20 hours apart, to trigger the development of eggs and induce spawning by bringing the fish into reproductive condition.
By injecting the Clown loaches with a commercial pituitary extract from another fish species, it was possible for Mihajlov to trigger ovulation in the females. The eggs were then removed from the females using a non-invasive technique called hand-stripping; the milt of the males was extracted, and the eggs were fertilised in a mixing vessel and then incubated.
The same technique is believed to be used by commercial fish farmers in South East Asia to produce large quantities of Clown loaches to sell to the aquarium trade.
Breeding Clown loachesThe adult brood stock, which were around eight years old, consisted of a single female and two males, which ranged in size from 12-15cm/5-6.
Mihajlov told Practical Fishkeeping that he has been trying to breed the species in this way for the past two years. However, the quality of the eggs produced by the female had not been of sufficient quality and several previous spawnings failed.
This time the female produced thousands of eggs and a few hundred of these were fertilised successfully.
The eggs were hatched artificially in an incubator into which air bubbles were injected. The eggs started to hatch after 18 hours at 26.5 degrees Celsius, and the fry started to eat Artemia nauplii just one day later.
Mihajlov told Practical Fishkeeping that the fry started to develop four vertical stripes by the second day, and that the fourth stripe starts to disappear as the fish get older, leaving the distinctive three-striped pattern of the adult.
The brood stock, which were obtained from suppliers in Singapore, were kept in a 200 litre aquarium with soft water (GH 8, KH 4).
Initially, Mihajlov kept six fishes in the tank but eventually selected the best three, based on their reproductive abilities.
Hormone induced spawningThe use of hormones to induce spawning in fish is a strategy rarely used by fishkeepers, and should only be attempted by trained professionals.
Hormone induced spawning is widely used in aquaculture and by many commercial fish farmers to allow them to spawn difficult fishes that would otherwise be very challenging to breed; a range of difficult-to-breed fish species sold in the aquarium trade are believed to be produced in this manner.
Mihajlov told Practical Fishkeeping that he is using the same hormone induced spawning technique to breed Synodontis, Labeo, Botia and other difficult species. He has already successfully used the technique to breed four other loach species, including Botia almorhae (formerly lohachata).