Another possible indication of
stress in the cobia reared at 5 ppt was the lack of mucus
on the exterior of the fish. While this was not
quantitatively measured, fish were handled weekly
during the weighing process and there was a noticeably
lower amount of mucus covering the skin of fish reared at
5 ppt in comparison to the fish reared in the 15 and 30 ppt
treatments. This is contrary to what would be expected
from earlier research which suggests that mucus
production in fish is increased after handling or in
response to temporary salinity changes (Sheppard,
1994). This perceived lack of mucus did not seem to
affect the growth of fish reared at 5 ppt, but may be
indicative of a decreased resistance to opportunistic
pathogens.