Breeding Orchid Dottyback - Part 2

Pseudochromis fridmani

In the last article I explained how I had raised a brood of Pseudochromis fridmani to 35 days old but had failed to get them through metamorphosis. In this article I will cover the techniques I learnt to raise these fish to adulthood. There were a number of problems that I seemed to be facing with raising these fish, firstly keeping a constant supply of highly nutritious food, keeping the fry in a suitable environment to prevent physical problems from head bumping and finally reducing mortalities from bacterial infections.

New Setup

The set-up I now use consists of a 24x12x12 tank for the larvae, a 160 litre sump and a 24x15x15 grow out tank. The larval tank is connected to the sump via a UV sterilizer and a pump. The sump also contains a small skimmer and media for biological filtration. Inside the larval tank are four airlines set one in each corner with a very low rate of bubbles emerging. The outflow of the tank is covered by a sieve with mesh size large enough to allow rotifers and Artemia through but not larval fish. Above the tank are two 55w power compacts that are on timers for thirteen hours a day.

Trying Again

By now I was able to predict the time of the eggs hatching within an hour and the parents were laying eggs regular as clockwork every 6 days. The female was still getting slight damage to her fins during spawning and the male would spend almost all of his time in the nest whilst he brooded eggs. By removing the eggs from the parents on the night they were due to hatch I was able to ensure that all of the larvae emerged. It is important however to ensure that only the number of larvae that I could raise were kept, taking too many could jeopardise the whole brood if I ran out of food. The newly hatched fry are placed in the larval tanks which contain rotifers and phytoplankton as the rotifers food source. The larval tank is isolated from the rest of the system and simply flushed through twice a day. This means that the larvae are living in an environment that has a constant supply of enriched rotifers, it also means that I do not have to constantly feed the larvae as I would on a flow through system. The other advantage is that the water is constantly greened up with phytoplankton. This seems to have a positive effect on the behaviour of the fry. P. fridmani larvae are phototrophic and in a tank of clear water they are constantly heading for the brightest spots in the tank, bumping against the sides and congregating in corners. The overhead lighting, green water and bubbles in each corner of the tank keep the whole brood centred in the middle of the tank. The tanks are flushed through twice a day to provide clean water, the rotifers are collected with a large sieve from the outflow and returned to the tank, this enabled me to run broods without wasting huge numbers of rotifers and also makes for very low maintenance times.

Changing Feeding

I have now raised broods on a number of different types of phytoplankton and it is difficult to say which gave better results, however I found the 2:1 DHA:EPA ratio that I mentioned in the last article less successful, I now use a higher EPA than DHA content. I also mentioned in the last article that I had problems with mouth deformities with one of the broods, I was unsure as to whether this was due to physical damage due to head bumping or a nutritional deficiency namely vitamin C. I overcame the head bumping with the new tank designs and at the same time started adding vitamin C to both the food cultures and the brood tank itself. Since doing this I have not noticed any of the previous deformities. I am inclined to think that the problem was due to head bumping but I cannot be sure. The fry develop very well in this new system for the first 10-12 days, they feed exclusively on rotifers and are almost a centimetre long by day 12. At day 6-7 the fry go through their first obvious change as their digestive system starts to fold. By day 13 they are starting to need a larger food source and this is where things start to get more tricky. The easiest next food to offer is Artemia, but as I previously explained Artemia are a nutritionally poor source of food due to them not feeding until they reach the instar 2 stage and their tough exoskeleton. On day 13 I start to offer a few newly hatched Artemia which the fry readily take. Apart from the nutritional problems with Artemia there are also bacterial difficulties. Artemia can have huge numbers of different types of bacteria living on them, some of which may cause mortality in the fish. To try and minimise losses through bacterial infections I used a bacteriacide on the larval tanks with different levels of success on different broods.

Getting Older

Over the next few days more continued to change until by day 31 two thirds of the brood were juveniles whilst the other third were strong post larval. Most of the juveniles were now accepting small pieces of chopped shrimp, they certainly had hearty appetites always going for the biggest bits first, trying to cram, down pieces of shrimp half their size. Once the fry had been through metamorphosis for a few days it was fairly easy to get them to accept pretty much whatever I offered, frozen, dried, flake or pelleted food all went down with great gusto. The fry quickly learnt to associate me with food and I only had to walk past the tank and a tight shoal of stunning little fish would follow me up and down, pressed as close to the glass of the tank as they could get. By day 35 all the fish had gone through metamorphosis and I transferred seventy six juvenile Orchid dottybacks to a grow out tank. To provide cover I tied a number of pipe fittings into bunches and hung them in the tank, this made it easy to remove the pipe parts when cleaning the tank or catching fish. Territorial behaviour starts in these fish as soon as they have gone through metamorphosis and although it rarely caused any fatalities I found it helped to regularly transfer the most dominant of the group to another grow out tank. This seemed to promote growth spurts in the groups and reduced the chances of smaller fish being picked on by larger ones. The appetite of the fish did not get any less and they would happily stuff themselves all day long although I was limited to feeding them five times a day in the morning and evenings. Over the next few weeks they developed the more slender appearance of the adults and the most dominant developed the characteristic elongated tail of the males. By 12 weeks old they were coming up to 4cm long and ready to move off to new homes. They have settled in very well to other aquariums and grown quickly into adults, I have not been able to distinguish any differences in behaviour or appearance between wild caught and my captive bred fish apart from the captive bred fish being less timid. I have recently paired a wild caught female with an adult captive bred male and the final test will be to close the life cycle with this pair. It has taken a huge amount of effort, expense and time to learn how to raise these fish but it has been well worth it, the only question I have left is which species to try next?

Glossary

• Nannochloropsis - A species of marine phytoplankton (that has a high EPA profile).
• Isochrysis - A species of marine phytoplankton (that has a high DHA profile).
• DHA and EPA - Essential fatty acids of the omega 3 family.
• DHA - Docosahexaenoic acid.
• EPA - Eicosapentaenoic acid.

By Clayton Smith

Photos By Robert Brady