Oreochromis niloticus picture (niloticus.jpg) by Beng Yong Tang
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| Size (cm): | 13.5 TL |
| Locality: | Singapore, Punggol Park Pond |
| Sex: | undetermined |
| Date: | 2004-07-16 |
| Remark: | O. niloticus is relatively new in Singapore, the O. mossambicus species was introduced during World War 2 by the Japanese, from stocks in Java, and tilapia is thus locally called "Japanese fish" or "Java fish". After the war, O. mossambicus was introduced to Hawaii from stocks in Singapore. The local O. niloticus may be introgressed hybrids from Red tilapia hybrids, with cross-breeding with feral O. mossambicus a possibility. The O. niloticus type tilapia (vertical bars on tail fin, smaller mouth) is found in relatively small numbers in Punggol Park Pond and Jurong Lake, areas formerly teeming with O. mossambicus. Feral Tilapia stocks in Singapore have crashed since the early 1990's, possibly due to hybridization with newer Oreochromis spp. The hybrids may be less viable in the wild (lower salinity tolerance, take longer to become sexually mature and do so at a larger size, sex ratios in offspring skewed towards more males, etc). This hypothesis remains to be verified. Other factors include many new non-native organisms being introduced including many new world cichlids like Cichla spp., Parachromis managuensis, Cichlasoma urophthalmus, and one old world cichlid, Etroplus suratensis. |