Tinfoil barbs caught in Portuguese waters

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Portuguese scientists have documented the first ever occurrence of the Tinfoil barb, Barbonymus schwanenfeldii, on the Iberian Peninsula.

The report, published in the most recent volume of the Journal of Fish Biology, is based on two male specimens, both under 20 cm in length, caught in August 2005 by fisherman maintaining the fish stocks of the Lucefcit Reservoir, Southern Iberia.

In addition to Barbonymus schwanenfeldii, four other alien species where collected from the reservoir, including Carp (Cyprinus carpio), Pumpkinseed (Lepomis gibbosus), Largemouth bass (Micropterus salmoides) and Zander (Sander lucioperca).

Prolific breedersIn its natural environment in South East Asia, Barbonymus schwanenfeldii has been reported to lay up to 7,900-16,000 (for fish weighting 220-382g) after an upriver migration to favorable spawning grounds.

Upon hatching, larvae and juveniles are reported to congregate in flood forest and grassland, and lakes.

Gonadal examination of the two Portuguese specimens of tinfoil barb revealed that they were both sexually immature.

Despite this, the scientists believe that the stable thermal conditions of the numerous reservoirs and dams of the regions would provide favorable habitat for tinfoil barbs if more were released.

Additionally, the scientists suggest that the numerous rivers flowing in to these reservoirs could provide suitable spawning grounds, with seasonally flooded areas providing nursery grounds for larvae and juveniles.

With only two male specimens of tinfoil barbs recorded to date, it is unlikely that this large cyprinid species has become established in the water bodies of the Iberian peninsular but their presence could possibly leave a more lasting impact.

Parasites and diseasesThe Portuguese scientists believe that the parasites and diseases carried by Barbonymus schwanenfeldii may also impact native species.

Several species of protozoan and parasitic nematode have been discovered on B. schwanenfeldii.

If introduced, these organisms may have a more immediate effect on native fish species of the Iberian Peninsular, several of which are found no where else, as they may have little or no resistance to new diseases or parasites.

The scientists suggest that aquarists, releasing pet Barbus schwanenfeildii that had become too large for their aquariums, are the most likely source of the introduction.

Aquarists are similarly blamed for the introduction of this species to the southeastern US and the Philippines.

For more information on the first Iberian record of B. schwanenfeldii see the paper: Gante, HF, L. Moreira da Costa, J. Michael and MJ Alves. 2008. First record of Barbonymus schwanenfeldii (Bleeker) in the Iberian Peninsula. Journal of Fish Biology, 72: 1089-1094.