A British fishkeeper has provided photographic evidence for one of the first documented captive spawnings of the Clown loach, Chromobotia macracanthus.
Colin Dunlop from Carluke, Scotland, who is an occasional contributor to Practical Fishkeeping magazine, reported on Saturday that his group of four Clown loaches had laid several thousand eggs in a spawning tank.
Dunlop told Practical Fishkeeping that his four Clown loaches, which are around four or five years old and 14-20cm in length, had started acting strangely and were cruising around the tank in mid-water.
The largest fish, a 20cm female, was being followed around the tank by three males in what Dunlop believed might be pre-spawning behaviour, so he moved the fish from their 1100 litre/300 gallon aquarium to a smaller 90 x 45 x 45cm/36" x 18" x 18" spawning tank.
"The rear fish were often at her vent and they were cruising around the tank together quite quickly," Dunlop told Practical Fishkeeping.
"They are quite sociable with each other normally but this was a bit different. It stuck out as all four were joining in. They are normally quite active and not shy at all."
Breeding tankThe tank, which had a plastic grid over the bottom to catch the eggs of egg-scattering fishes, was equipped with a number of plastic pipes to allow the fish to shelter, and like the main aquarium had a very low pH of around 4.5.
Dunlop told Practical Fishkeeping that when he later checked the spawning tank he saw the fishes' tails waggling from inside the pipe and saw thousands of eggs in the water.
Said Dunlop: "I literally jumped when I saw the eggs. I wasn't really expecting it at all. It was ridiculously exciting and the urge to watch was horribly conflicting with the need to leave them to it.
"The eggs were noticed about an hour after lights-on in the shed. They have a 12-hour photoperiod with no outside light."
Unfortunately, many of the eggs appear to be infertile, however, some of them remain amber in colour and it is hoped that these eggs may be viable.
Low pH, low temperatureOne of the possible reasons for the spawning could be the low pH at which the fish are kept.
"The main tank, where the fish have been for the two years is very soft and acidic," Dunlop said.
"The pH normally sits around 4.5, and up to about 5.5 after a water changes, but drops quite quickly. The newly set up tank had a pH of 7.2 as it was just raw tapwater having sat for about 24-hours, so I reduced the pH down to 4.5 with hydrochloric acid.
"I tested the TDS after seeing the eggs and it was about 75ppm. The pH dropped to 4.1 a day after spawning. According to my local water test, as per the Practical Fishkeeping site, the GH is 3.
"The last time I checked the tapwater, the nitrate was about 10ppm. I think that might be a good trigger, as I bet the big tank is quite high with so many big fish in it.
"Also, the temperature in the shed is controlled by space heating and it takes a day or two for a tank of tank water to get to room temperature.
"They went into the breeding tank at 20 degrees C and I saw the eggs at 25 degrees C, so perhaps that is a trigger as most people keep their Clowns really warm. The main tank is at 27 or 28 degrees."
Infertile eggsSadly, a significant proportion of the eggs laid have turned white, which is typically an indication that they are infertile. A small number - about 20 out of several thousand - remain amber in colour, and it is hoped that these might be viable eggs.
Dunlop says that moving the fish to a breeding tank might have been the mistake that led to so many of the eggs becoming infertile.
Dunlop told Practical Fishkeeping: "One theory suggested by Kamphol Udomritthiruj is that they were spawning or about to spawn in the main tank. I disturbed them by catching them and the female expelled the eggs a couple of days late.
"My main tank is not directly lit, so it is possible I wouldn't see eggs being laid in there and there is a stack of fish in there that would hoover them up, so perhaps I missed it.
"If Kamphol is right, then there was no trigger caused by me that I am aware of, other than cleaning a sponge filter in the tank. I hadn't done anything the week prior to the spawning behaviour.
"This has certainly encouraged me to keep an eye out for diamond-shaped behaviour again," Dunlop added.
While several fishkeepers have claimed to have had bred Clown loaches, few have been able to provide evidence of the spawnings.
British fishkeeper, Granville Hammond, claimed to have spawned Clown loaches in an article published by Practical Fishkeeping in 1996.
However, Hammond has never provided evidence of the spawning. See: You can breed Clown loaches.
The species has been spawned in fish farms with the aid of hormones to trigger spawning. Farmed fish are available from Asia and breeders in the Czech Republic but there have been no reports detailing the exact methods used.