Limnology and Oceanography, November 2003, Vol.48(6), pp.2392-2396
Herbivorous fish feed on cyanobacteria. Digestability differs, however, between cyanobacteria species without mucous cover and mucilaginous genera such as . The latter can pass fish guts almost undamaged, and it has been hypothesized that they can take up nutrients during gut passage. Here we tested whether live , as food for juvenile roach labeled with P, indeed showed higher radioactivity after gut passage as compared to gut contents in control experiments with fish fed heated . showed high viability after passage through roach guts, and live colonies had a significantly higher radioactivity than dead ones. We conclude that is protected against digestion in roach guts and can directly use the phosphorus supplied in the fish guts during passage.