An ethopharmacological analysis of morphine effects in fish (Macropodus Opercularis).

The behavioural effects of morphine on fish (Macropodus opercularis) were studied by an ethopharmacological analysis. For this purpose active and passive behavioural units were observed. The results show that morphine treatment had a stimulating effect. However, the treatment resulted not in a general enhancement of active behavioural units, but in a selective increase of some of them, such as swimming and erratic behaviour, or in stereotyped behaviours, such as circling. By contrast, high dosages of morphine resulted in a decrease of escape and of standing under the surface behaviours.