Just for a change, I went back to the 'old fashioned' way of breeding Danios. When I first started keeping fish, the late John Marshall of the Medway club, bred and raised literally thousands of Danio rerio and the so called 'frankei' (actually also rerio) each year. All were spawned over a bed of marbles. Having a fair stock of them that had not been used for many a long year, I had to acquire a few dozen more. The local paper shop was just a bit inquisitive why a 'senior citizen' should want several bags of marbles. Eventually, curiosity got the better of them and I told them what I would be using them for. As they say, it takes all sorts to make a world!
Back to the breeding. I used an 18 x 12 x 12 inch tank and placed a layer of marbles over the bottom. I used a mix of hard and rain water so the hardness was possibly around 7 deg . The temp in the fish house on the top rack is approx 25°C. Unusually, I did not condition the males and females separately. This probably led to a reduction in the number of fry but as I have around forty, that is a successful spawning. They were placed in the spawning tank late in the evening. My new fish house does not have access to sunlight but I do have a 15W bulb on a dimmer switch on all night. At approximately 08:30, a 60W bulb on a timer comes on. I then manually put the main lights on at around 09:30 and turn off both of the others. Almost immediately the main lights were put on, the males started flaring at one another and at the females. There were no obvious signs of eggs being expelled. I left the adult fish in place for another 24 hours and then netted them out. After 48 hours, fry could be seen hanging on to the tank sides. After a further 48 hours, they were free swimming. At this stage, I removed all of the marbles from the tank base. I then added a couple of large ampullaria snails to mop up any uneaten food. I commenced feeding ZM000 dispersed in a little tank water several times a day. After 5 days, just a tiny amount of newly hatched brine shrimp was also added. Some fry seemed to be just about able to cope with it, so it was decided to continue both ZM000 and brine shrimp. At ten days, they were fed just brine shrimp twice a day. After twelve days, I started to do a twenty five percent water change each day. Growth was quite rapid and after four weeks, they were about one cm long. At this stage, most were distributed to club members who wanted to participate in the 'fry rearing competition'. It will be interesting to see the fish when they are brought back for judging in November 2006. It is believed that this is the first time this species has been captive bred.
© P.W.Cottle. Strood & District Aquarist Society 2006.