UK - Aquaponic systems offer many benefits but the impact it has on the welfare of fish is generally unknown, explained Bjoern Bassmann, University of Rostock, in his presentation at Aquaculture Europe 2016, 20-23 September, Edinburgh, Scotland.
In his study, Mr Bassmann set up two African catfish systems – one a floating raft aquaponics system and the other a RAS control.
The aquaponics unit had a volume of 2120 litres and the RAS 1370 litres.
Each unit was stocked with 18 catfish fed 25g as a single dose per tank each day for 87 days.
Cucumbers were grown on each system and water parameters were measured daily.
Mr Bassmann then took blood samples from the caudal vessels, recording plasma cortisol and blood glucose levels.
He also examined external injuries on the fish and measured fish growth performance.
The final weights of the fish were fairly similar between the two systems. In the aquaponics unit, final weight was 333.3g and 327.6 in the RAS.
Similarly, plasma cortisol and blood glucose were roughly the same in both systems, though males in both systems had higher blood glucose levels than the female fish.
In terms of external injuries, the fish in the aquaponics system fared much better, with less injuries reported and many with no injuries.
This significant difference is thought to be related to water parameters and is more likely based on alternated fish behavior.
In conclusion, Mr Bassmann explained that although the two systems showed similar results, the smaller amount of external injuries in the aquaponics system is very positive for the welfare of catfish.