Use of additives
are available that can be added to the transport water to improve the transport
results and allow fish transport over longer periods.
using filters and water re-use systems, additives can be applied to the water
to give similar effects. Addition of seawater to freshwater will have a
positive pH regulating effect because of its buffer-ing capacity. The same will
be the case with addi-tion of other buffering substances. Sodium chloride can
be added to freshwater as a defoaming agent. Addition of clinoptilolite to the
water (as used in an ion exchanger) will reduce the concentration of ammonia.
Addition of salt
may reduce osmoregulatory disturbance, and by this the total stress when trans-porting
freshwater fish. Antibiotic can be added to reduce the development of bacteria
in the trans-ported water.
sedatives, such as MS222 and clove oil, to the transport water may also be done
to calm the fish down and reduce the metabolic rate. This will
reduce oxygen consumption and decrease the excess of carbon dioxide and
ammonium ion; the fish will also tolerate more stress.
All use of
additives will, however, require accurate control of the water quality during
transport; they may not always function or the effect may be minor. It is best
therefore normally to avoid using additives. Adding of antibiotics and
sedatives ought to be avoided unless there are very special conditions
pertaining to the live transport. These may not be allowed before the fish go
to process-ing plants because they may leave residues in the flesh.