The Israeli Journal of Aquaculture - Bamidgeh 53(3-4), 2001, 147-157
GROWTH PERFORMANCE OF HYBRID BASS
AND HYBRID TILAPIA IN CONVENTIONAL
AND ACTIVE SUSPENSION INTENSIVE PONDS
A. Milstein¹ *, Y. Avnimelech², M. Zoran¹ and D. Joseph³
1 Agriculture Research Organization, Fisheries Department, Dor,
MP Hof HaCarmel 30820, Israel
Corresponding author: A. Milstein email@example.com
2 Faculty of Agricultural Engineering, Technion, Haifa 32000, Israel
3 Ministry of Agriculture, Fisheries Department, Dor, MP Hof HaCarmel 30820, Israel
(Received 22.8.01,Accepted 21.11.01)
Key words: active suspension intensive ponds, hybrid bass, hybrid tilapia, water quality
Recently developed, active suspension intensive ponds are based on the idea that fish ponds (aerated
and mixed as required for the well-being of the fish) can also serve as water purification units.
The present paper compares water quality and fish growth in conventional intensive ponds (daily
water exchange 500%), with active suspension intensive ponds (daily exchange 8%). The fish tested
were hybrid tilapia (Oreochromis niloticus x O.aureus), already known to perform well in active
suspension units, and hybrid bass (Morone saxatilis x M.chrysops), which is commercially cultured
in conventional intensive ponds.
Water quality in the two types of intensive ponds differed as a result of the "internal water purifi-cation"
vs "external water purification" approach. Bacterial development was greater in the active
suspension ponds. Several parameters were affected by the different rate of water exchange, including temperature and removal of ammonium. The latter was lower in active suspension ponds
due to reduced washout of particles and their associated nitrifying bacteria. Nitrification was
greater in tilapia active suspension ponds because of grazing by this fish. Active suspension units
operated with less than 2% of the water used in the conventional intensive ponds. Hybrid bass and
hybrid tilapia performed similarly well in both types of pond, indicating the economic advantage of
culturing them in the water-saving active suspension system. Tilapia graze on suspended particles, leading to additional savings in feed costs. The good performance of hybrid bass in active suspension ponds is herein reported for the first time.