UMT MOOC: Ornamental Fish Culture - Topic 6: Ornamental Fish Breeding - Selective Breeding

We're going to review back on why ornamental fish is one of the growing sector in the aquaculture in MY. Since the last few decades, due to its geographical location, MY is one of the largest exporter of ornamental fish of local and exotic species. The main producers are from the state of Johore (83%), Perak (14%), and remaining states of Selangor, Malacca, Negeri Sembilan, and Pahang (3%). Note that statistic are from the slide. These ornamental fish farms are mostly family-owned and more than 95% of fishes are for exporting. Therefore, if you want good quality fishes, buy directly from fish farms (only if they are willing to sell to consumer directly) instead of aquarium shop.

Fish with good quality and different varieties boost production of ornamental fish and economic gain in the aquaculture industry. Selective breeding is one of the technique through many generation of breedings to obtain the desired traits (morphology and colourization). This technique is based on the genetic manipulation of genotype (genetic makeup) to obtain quality phenotype (characteristics or traits). In other words, phenotype is the physical expression of genotype. The figure (Tave, Douglas. (1995). Selective breeding programmes for medium-sized fish farms.) below illustrates the relationship of selective breeding.

For something else more visually appealing of genetic tree, see the screenshot of Gene tree of Nishikigoi from International Nishikigoi Promotion Centre (INPC). This is a good example of showing how selective breeding works by breeder to obtain certain traits, in this case, colours and patterns.

There are several selective breeding categories which are:

(1) In-breeding.
This type of breeding is used to mass produce a stable quality traits of fishes like colours, patterns, and fins. Breeding is done through genetically close broodstock.

(2) Line-breeding
Similar to in-breeding but only selected traits of the ancestor or ancestors were targeted in breeding. Selected good traits of flaws were identified either to retain or remove in next generation. Such breeding method is very time consuming as the breeder needs to select and keep track of good fish population to continue the next breeding generation. Betta sp. are mostly breed using this method.

(3) Out-cross breeding
Use this method when you want to diversify the genetic of the fishes to reduce possible genetic anomalies and diseases.

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