An early myopathy affecting the myotomes of a stock of sea bass is des
cribed, By electron microscopical examination different degrees of mus
cle lesions were first detected in recently hatched larvae, Muscle fib
res underwent a degenerative process, that according to the gravity of
the lesions and age of the fish was sequenced in four stages. Necroti
c muscle fibres were abundant in the myotomes of post-larvae (more tha
n 60 days). Although this degenerative myopathy is non-specific, the i
mportance lies in its progressive sequence, Vitamin E-selenium deficie
ncy and uncontrolled peroxidation of the lipid content in the feed is
thought to be the cause of the problem. The possible implication of th
e myopathy in the appearance of a high percentage of lordosis in the s
ame stock of sea bass is discussed.