Advances in Ornamental Aquaculture

In my last two articles I covered some techniques that can be used to successfully breed and raise the fry of some of the more common species of ornamental marine fish that we keep, in this article we will look at some of the fish breeding success stories from around the world and the advances that have been made in the ornamental marine fish breeding industry.

Despite the fact that in comparison to factors such as sedimentation, dynamite fishing and pollution the collection of fish for the aquarium industry has a far smaller impact on natural reefs it cannot be denied that the removal of fish for the aquarium industry is, in some cases having a negative effect on the abundance and diversity of fish on the worlds reefs. The status of the worlds reefs is unlikely to improve in our lifetime so the development of the ornamental aquaculture industry is important not just from a conservational point of view but also to ensure that we have a good supply and diversity of fish available to us.

The commercial breeding of ornamental marine fish is by no means easy, not just because of the difficulties in rearing larval fish but also because of commercial constraints. Many species of fish simply cannot be raised yet as we do not have a great enough understanding of their requirements and life cycles, others can be raised but as yet have only been done so on small scale experimental operations. Even those that can be raised in large numbers can prove uneconomical due to the huge amounts of time and money that need to be invested to do so. Many aquaculture companies today are focusing on rarer species of marine fish to breed that have high retail values and can therefore be competitive with their wild caught counterparts.

There are over 800 species of marine fish that are traded within the aquarium industry, of those only 4% are captive bred on a commercial scale, that leaves over 750 species of fish that have never been cultured in captivity. Species that are regularly bred on a commercial scale include clownfish, dottybacks, seahorses, some species of goby and several species of shrimp. However, the good news is that the list of fish that have been successfully raised to adulthood in captivity is far greater even though some of the species have only been raised in very small numbers. Table 1 contains a list of all the marine ornamentals that have been bred in captivity to date: * indicates species that can be produced commercially. There are a number of companies now involved in ornamental marine fish aquaculture, one American company that is leading in this field is Reef Culture Technologies, they have successfully bred many of the species of fish shown in the table and have made many breakthroughs particularly in Centropyge culture. The larvae of Centropyge species require a smaller, more highly nutritious food source than many of the other species of fish that are bred, combining that with a high sensitivity to environmental changes along with a longer period of time to reach metamorphosis made them a challenging group to raise.

On November 3rd 2001 Reef Culture Technologies successfully closed the life cycle of the Fishers angelfish (Centropyge fisheri), this was the first documented time that this species had been raised and they have subsequently raised several other  species of Centropyge including C. flavissimuss (Lemonpeel angel), C. loriculus (Flame angel), C. multicolor (Multicolor angel), C. interruptus (Japanese pygmy angel), C. respendens (Resplendent angel), C. colini (Colins angel), Paracentropyge multifaciatus (Multibarred angel), Apolemichthys arcuatus (Bandit angel) and C. debelius (Debelius angel). All of these were industry firsts according to RCT ltd and they have also gone on to produce Centropyge hybrids crossing C. resplendens with C. fisheri.

The first attempts to raise C. fisheri concentrated on using rotifers and ciliates as a first food, however there was little success using this technique and larvae would die at around five days old when they had exhausted their yolk sacs. The breakthrough came when RCT ltd starting using copepod nauplii as a first food instead of rotifers and ciliates. The eggs of Centropyge species are very small and hatch after only 16-18 hours in comparison to other species such as dottybacks which hatch after 4 days or clownfish which are even longer. With such a small amount of time passing from fertilisation to hatching the larvae of Centropyge species are understandable very small. C. fisheri larvae are around 2mm in length on hatching, have no eyes, mouth, digestive tract or functioning fins. The larvae do not feed on hatching, gaining all their nutrition for the first four days from their yolk sac. From four days old the larvae can start feeding and by the time they are 45-50 days old they have gone through metamorphosis.

RCT ltd put the success of their rearing Centropyge species down to the use of copepod nauplii as a first food over more established food types. I covered some of the benefits of using copepods as a larval food source in my previous article and much of the research that is ongoing today incorporates the use of these animals as a food source for rearing some of the more difficult species of marine fish. The advantage of using copepods is largely due to their excellent nutritional profile, they are high in proteins, highly unsaturated fatty acids, amino acids as well as being rich in digestive enzymes. The problem with them, and one of the stumbling blocks in using them as a larval food source is their lengthy reproductive cycles. Both rotifers and Artemia can be produced very quickly and in very high concentrations for aquaculture however copepods are much slower to reproduce and require better water conditions and feeding than other live food cultures such as rotifers. It is partly due to the higher overheads incurred in culturing copepods that have resulted in many species of fish being uneconomical to produce on a commercial scale. Advances in copepod culture will inevitably lead to more species of fish being commercially bred.

Here in the UK we have our own company Tropical Marine Centre that has been at the forefront of ornamental aquaculture for many years and have a healthy list of fish and shrimp that they have successfully raised (see table 2).   TMC have also bred a couple of world firsts including Fire shrimp in 1997 and Pipefish (Doryhamphus multiannulatus) in 1999. The TMC hatchery consists of 160 tanks utilising 35,000l of water and can hold up to 50,000 fish at any one time. They export their captive bred fish to over 25 countries and sell up to 100,000 fish per annum. In the last few years TMC have seen some colour variations in their batches of Amphiprion ocellaris and have selected these and continue to produce them under the name of Snowflake clowns. These are a naturally occurring colour variation of A. ocellaris which due to their rarity fetch a high price within the aquarium industry.

There are also a number of companies in the USA that as well as breeding and raising fish in captivity are collecting fish at the larvae or post larvae stage of development from the oceans plankton and then raising these larvae in captivity to go on to sell. Although these animals are still being collected from the wild they are collected at a time when they would naturally have a very low survival rate and so there is very little impact on the species population. There are a number of fish that are being supplied this way that have not yet been bred and raised in closed systems, these include several species of Pomacanthus angel, butterflyfish and tangs.

It is not just large private companies that are involved in breeding ornamental marine fish, there are a number of hobbyists in the UK that are successfully and regularly producing low to moderate numbers of fish that they distribute to local retail outlets. Most of these are involved in the breeding of species of clownfish, seahorses and dottybacks, I myself have raised small batches of Amblyglyphidodon ternatensis (damsels), clownfish, seahorses and Orchid dottybacks on a small commercial scale, however it is not easy to turn small scale breeding programs into large profitable commercial ones. Despite this small scale ‘garage’ operations can be profitable and also help to provide local retailers with a slightly greater availability of captive bred fish.

Public aquariums in the UK have also had some success with captive breeding programs. Notably the Blue Reef Aquarium in Newquay have bred various species of clownfish, seahorses, pipefish and Bangaii cardinals. Public aquariums are prohibited from selling any stock direct to the public or retail outlets but breeding programs enable them to pass surplus stock onto other public aquariums reducing the need to exhibit animals taken from the wild. Interestingly The Deep public aquarium in Hull has a breeding program of Blue Spotted rays. These rays have a notoriously poor survival rate when taken from the wild with many animals dieing in the collection and shipping process, hopefully it will not be too long before the only blue Spotted rays available in retail outlets will be ones that have been captive bred and are well adapted to aquarium life.

It is encouraging to see that the variety of ornamental marine fish that have been successfully raised in captivity has greatly increased in the last 10 years, unfortunately though most of these species are still uneconomical to produce in comparison to the collection of their wild caught counterparts. One of the main stumbling blocks is the costs of large scale production of appropriate live food items. As new techniques are developed for the economical production of live food and the understanding of the requirements of larval fish increases, then we will soon see more examples of those species that have already been successfully bred being produced on a commercial scale. The demand for ornamental marine fish is increasing as the industry grows as a whole and with further developments in aquaculture techniques we are likely to see more and more species of captive bred fish available in retail outlets and it is good to know that there are plans for further developments in this field both in the UK and overseas. As hobbyists you can support this advancement by buying captive bred fish wherever possible safe in the knowledge that those fish are better suited for aquarium life and have had no negative impact on natural reefs by their removal from the wild.