FEVER IN GOLDFISH IS INDUCED BY PYROGENS BUT NOT BY HANDLING

Six goldfish, Carassius auratus, weighing 2.5 to 4 g were placed indiv idually in an aquarium with two communicating chambers. One chamber wa s thermostatted at 34 degrees C, the other at 37 degrees C. In control Session a, without external intervention, fish selected the cooler ch amber most of the time and stayed only 4.8 +/- 1.1 min/2 h at 37 degre es C. In Session b, infectious fever was assayed: pyrogen (Salmonella typhosa LPS, or human interleukin-2) was injected intracranially and f ish stayed 44.7 +/- 15.3 min/2 h at 37 degrees C. In Session c, behavi oral stress was achieved by chasing the fish with a net, catching it, handling it out of water, and injecting 10 mu L of saline intracranial ly. Fish stayed 2.7 +/- 1.0 min/2 h at 37 degrees C. Analysis of varia nce showed that stay at 37 degrees C was significantly longer in Sessi on b than a and c, and that Sessions a and c were not significantly di fferent from one another. This result confirms the existence of behavi oral fever, but does not support the hypothesis of fever in fish after handling. (C) 1998 Elsevier Science Inc.