sera guide - Healthy pond fish

39 Cause: page 22 Prevention/Recommendation: You should urgently avoid strong conductivity variations, as they may occur when transferring fish or when carrying out a large water change. The sudden change to a considerably higher or lower salinity than the usual one cannot be compensated by the fish. If fish are transferred from water with a high conductivity (high salinity) into water with a lower conductivity without an adap- tation phase they will suffer from an osmo- tic shock (also the other way round). The mucous membrane comes off, and the organism of the fish is extremely stressed and weakened. Secondary diseases occur frequently. In case of large conductivity dif- ferences, the fine cartilaginous joints in the fin rays can burst due to the high osmotic pressure. The fins then fall off in large chunks. Avoid osmotic shocks by checking the pH value and the conductivity of the transport water and the pond water before transfer- ring the fish. If in doubt, and if you do not have a conductivity meter at hand, please ask your retailer whether the fish were kept under salt addition when purchasing new fish. You must of course also be careful when re-transferring fish from a salt bath. The fish are generally less sensitive to con- ductivity increases, i.e. when adding salt. Rather quick addition of salt improves the therapeutic benefits of a salt bath. However, you should nevertheless adjust the con- ductivity stepwise if you want to maintain a high final concentration. Adaptation can be achieved by adding water containing less salt to the water that contains more salt or by adding sera ecto- pur to the less salty water. Differences be- tween 100 and 200 μS/cm are negligible [for example, a single preventive dosage of sera ectopur with 0.1 g/l or 5 g per each 50 l (13.2 US gal.) increases the conductivity by only 200 μS/cm]. The water conditions can be adjusted to the according desired levels in small steps with adaptation phases of several hours each. Osmotic shock 8 Preventing and remedying maintenance mistakes and intoxications