Research into the use of recirculating aquaculture systems (RAS) addresses the question of how to achieve profitable production while consistently recycling water and nutrients with minimal fresh water demand and waste production. The RAS facilities require an adequate supply of fingerlings, and a facility for fingerling production in conjunction with each RAS can prevent disease transfer and ensure quality and continuous production. The time, space, and financial investment can be eliminated by hatching (purchased disease free ova) and rearing of fingerlings every 2-3 months. The present study evaluated (water quality assessment, feed utilization, production cycle duration) a simple low cost recirculating hatchery for salmonids as a safe and continuous source of fingerlings for further rearing in RAS. The tested recirculating hatchery enabled low cost efficient production on a small scale (at least 5 production cycles per year, > 63 000 fingerlings per each cycle), low fresh water demand (0.05 l.sec-1) with maintaining good rearing conditions, and environmental and zoohygiene safety. Such simple facilities can support the sustainability of inland aquaculture and strengthen the effort to deliver quality products with minimal operational and environmental costs.
See my link for 70 fish farm systems on land, comprising more than 8,000 on land fish farms around the world. There is no need anymore for the excessive environmental damage caused by in-ocean fish farms: http://fishfarmnews.blogspot.ca/2012/01/key-document-34-mostly-on-land-closed.html.
Some more text from the study:
The positive results obtained in a simple recirculating system call into question the reported need to use additional technologies for hatcheries such as UV treatment, ozone application, microsieve filtration, oxygenation, and aeration. The RHS was fully functional without such treatments, thus is more efficient with respect to initial investment as well as operating costs. Nevertheless, potential use of additional technologies in enhance the RHS should be discussed. Added aeration and oxygenation may increase the capacity of RHS, but benefits such as increased production and increased biofiltration rate are cancelled out by increased operating costs. Oxygen level and biofiltration efficacy were found to be sufficient in the current study. -
See more at: http://www.thefishsite.com/articles/2001/a-simple-and-effective-recirculating-hatchery-for-salmonids#sthash.sdp4Ved9.dpuf.