A scientist collects blood sample from a carp found in one of the study sites. Lower photo: Smaller testes of the carp makes it “feminized”, indicating pollution in sample site.


The common carp, known as karpa in the local market, can possibly help in detecting the magnitude of wastes in water ways.

In a study conducted by Dr. Michelle Grace V. Paraso of the College of Veterinary Medicine, University of the Philippines, Los Baños, carp was found to have a potential use as a biomarker in detecting the level of pollutants in the country’s water resources.

The study evaluated carp as fish biomarker in determining the contamination of Laguna de Bay in four sites: Sta. Cruz and Paete, Laguna (East Bay) and Taguig City and Muntinlupa City (West Bay).

A biomarker is an organism with a particular substance which may serve as indicator of some natural phenomenon like pollution and various biological pressures like infection and disease. 

Dr. Paraso found that majority of the male carps in study site have shrunk testes compared with that of the normal male carp. Shrunk testes of a male carp indicate that the fish has been feminized. Such feminization shows that the carp was exposed to certain type of pollutant known as estrogen, among others.

According to the study, changes in the reproductive conditions of carp are influenced by several factors, such as food availability, water quality, and temperature.

Estrogenic contaminant or pollutant is estrogen produced through unnatural means. The contaminants developed from chemical components obtained in an environment and they cause reproductive impairment in water organisms such as fish.

Paraso is an expert from the Veterinary Medicine Division of the National Research Council of the Philippines of the Department of Science and Technology (NRCP-DOST) which funded this study. The study is relevant at this time when the government is pushing for a cleaner environment, especially in the coastal areas where many people live and obtain their livelihood. To know more about the services of NRCP, visit their website: (By Geraldine Bulaon-Ducusin, DOST-STII / Photos by Val Zabala, DOST-NRCP)