Share thisA functional view of racks for small fish.
Racks and tanks are important to fish health and facility functioning in today's biomedical aquatics facilities and the recent development of this field. This article will review several features central to good racks and good rack use. The many tradeoffs and technical details of these complex systems only permit presenting outstanding features, potential pitfalls, and future directions.
Historical Background
As biomedical aquatics facilities have become more sophisticated, they have assimilated techniques from various fields, such as aquaculture, animal care, ergonomics, and modern research genetics. Aquaculture easily adapted well-engineered water systems for zebrafish use. However, a well worked outway to hold and supply many tanks on a rack, while efficiently packing them in an easily accessible manner, was not immediately available.
Originally, more zebrafish researchers were familiar with home aquarists than aquacultural engineers. So, left to their own devices, they lined up rows of aquaria on shelves. Sophisticated set-ups had a water supply and drains for each tank. Less sophisticated set-ups had filtration equipment requiring maintenance for each tank. Thiswas elaborated upon until facility sizes increased and it became obvious that new, large facilities being set-up should be designed with more professional help. This was the beginning of specially designed, professionally built water systems and racks for zebrafish biomedical research facilities. These "racks" have evolved into a rack-tank system where the two major components, the rack and the tanks were designed to work together. Sadly the interlocking rack and tank components have, to some extent, ruled outmixing components between different manufacturers, thus reducing consumer choice.
When people left those early large labs to set up their own (usually smaller) facilities, they wanted smaller, more portable racks and water systems. To fulfill this need, "stand alone" racks were developed by removing the lowest tank rows from the racks and replacing them with a water system. In these racks, used tank water drains down to the water system where it is filtered, treated, monitored, and pumped back to the tanks. The tanks in these systems are usually at the ergonomically advantageous above the knee level.
Basic Rack Functions
Fish tank racks provide the infrastructure required by tanks, have useful features for researchers, and are now adapting to additional concerns like ergonomics and fish health. Water requirements are fulfilled by either a separate, centralized water system or in "free standing" racks, by their own water system. Aeration, a common option, can keep fish alive if water flow stops. Aeration-induced turbulence also keeps debris suspended so it can be removed by water exchange. Aeration can be supplied from a "free standing" rack, from a centralized facility, or by institutional air. Institutional air often contains oil and can therefore be problematic. Water disposal requires connecting to building plumbing via standard plumbing connections or a floor drain. Rack function can be impaired by inadequate water system water pressure, water flow capacity (pipe size), particulate load, and the appropriateness of the delivered water for the animals on the rack (pH, temperature, etc.). Rack water temperature is maintained either by the temperature of the rooms they are in, by heaters in the water system, or both.