BB Ch20 Other laboratory fishes Flashcards
Fish is a broad encompassing term. What 4 taxonomic classes contain fish?
Myxini, Cephalaspidomorphi, Elasmobranchiomorphi, and Osteishthyes
How have fish been used in research?
Toxicology studies (Japanese medaca and common guppy); fish models in study of cancer (zebra fish and swordtails); ecological studies of aquatic environments; and basic physiologic, biochemical, and molecular research
How much overhead clearance should a fish tank have?
The minimum overhead clearance for any tank should exceed the depth of the tank to allow the use of nets without impediment and facilitate safe handling of fish.
The major safety hazard in aquatic facilities is electrocution. What safety precautions should be employed to avoid disaster?
Use properly wired ground-fault circuit breakers throughout the facility. All electrical outlets should be 3-4 feet above the floor in case of flooding or inappropriate use of water hoses. Use rubber gaskets to seal moisture from outlets. Employees should be trained in safe use electricity near water. Floors should be sloped and drains positioned so there is no standing water. Dip nets should have nonconducting handles and there should be no exposed wiring.
How much does water weigh? Why is this a concern?
One liter weighs about 1 kg. One gallon of water weighs 8.3lbs. A 25 gallon tank (100 liters) will weigh over 200 lbs when filled. Support stands and flooring must be strong enough to accommodate the weight.
What are 3 types filtration used in aquatic design?
Mechanical, biological, and chemical
What is mechanical filtration?
It removes suspended particles from eater by passing it through a medium that obstructs the particles.
What is chemical filtration? Provide some examples…
Chemical filtration encompasses a wide range of methods for removing molecular contaminants from water, including ion exchange, foam fractionation (by protein modification and ultraviolet filtration), and activated carbon filters (nonspecific exchange filter).
What is biological filtration?
Biological filtration is biological fixation of wastes into less toxic compounds or forms. Bacterial fixation of nitrogen is the most commonly employed form.
What is usually the limiting factor in biological filters?
The limiting factor is the surface area for bacterial growth along with the ability to circulate the waste-laden water into contact with the bacteria responsible for nitrogen fixation.
What is a flow-through (or open) water system?
It is characterized by the continuous addition of new water with equal volumes being removed.
What are some disadvantages of a flow-through system?
Cost is a disadvantage of getting water from a municipal system as well as the expense of removing municipal disinfectants. Wells can fail if using well water. Another disadvantage is tempering and conditioning water and the disposal of effluent water from fish systems.
How can the air system for fish tanks transmit pathogens?
The fine bubbles coming to the surface from air stones and airlifts cast millions of small aerosol droplets into the air that can carry bacteria, viruses, and fungal spores.
How can fish tanks and water systems be disinfected between experiments?
Most commonly, the water in a system is drained and replaced after cleaning any visible dirt from the tank sides. A second method to decontaminate tanks is to spray 70% ethanol or 2-propanol and allowing the alcohol to evaporate (after cleaning visible debris). This method does not clean the plumbing or filtration systems. The final method is to drain and remove debris and fill the tank with a dilute chlorine or quaternary ammonium solution and circulate for an hour or more. Great care should be taken to ensure all disinfectant is removed from the system before it goes back on line.
What are some important considerations when retrofitting an existing animal facility for aquatics?
First evaluate potential water sources for reliability as well as quality. Also evaluate water disposal and cost. Next, look at the electrical supply. Electric resistance-based heaters, pumps, and lighting can double or triple the power requirements of the existing facility. In addition, ground-fault receptacles should be added and placed above splash points. Power-failure alarms and emergency power generators are a necessity for aquatic facilities and should support air supply pumps and generators as a fist priority, along with emergency personnel safety lighting. Also aquatic facilities will load large amounts of moisture in the air which will affect the air handling system.
What are important considerations when planning to build a new aquatic facility?
Will the facility hold fresh water species, marine species, or both? How large will holding tanks be to accommodate these fish? What shape will the tanks be (round or rectangle)? What will be the nature of the studies?
What is the optimal temperature range for tropical fish?
24-26ºC Temperature of 27ºC is sometimes used when treating protozoal infections.
How can fish tanks be heated?
Room air can be heated in the 24-25ºC range. Supplemental heaters should be used to boost temperatures in case of failure of the air-handling system.
What is the rule of thumb when predicting wattage of heaters of fish tanks against volume of water?
50-100 watts of heater/40 liters of water
How can water be cooled to maintain temperate or cold-water species of fish?
The most common refrigeration systems are heat exchangers driven by a compressible refrigerant. Titanium is the only metal proven suitable for heat-exchangers used in marine systems.
What is the ideal choice of tank construction for small water systems?
Glass is the ideal choice because it allows excellent visibility, it is relatively chemically inert, it is hard and less easily scratched.
Why should only high-grade or medical-grade silicone be used in glass tank construction or repair?
Low-grade, inexpensive silicone caulks contain heavy metals, cyanide, and organic toxins which can kill fish.
What is relatively inexpensive and probably the most commonly used structural plastic in aquarium construction?
Fiberglass (highest tension loading capacity of the plastics) is the most common however there is variability of toxins leaching from the hardening resins which makes it unsuitable for toxicology studies.
What plastic is a poor choice in any fish system?
Vinyl is poor choice for fish systems because it is easily damaged and has large residuals of toxic plasticizer and heavy metals trapped in the polymerization process.
Concrete is widely used for very large fish systems because of durability, low cost, and formability. How should it be treated before housing fish?
It should be thoroughly washed or leeched with dilute muriatic acid, then several coats of sodium silicate or other sealant should be applied.
Can metals be used in aquatic systems?
Stainless steel can be used (American Iron and Steel Type 316) but it will corrode. Titanium is preferred over SS where strength and maximal corrosion resistance are needed. The galvanized coat of iron can contain lethal levels of zinc. Bronze can also be a fatal source of zinc and copper.
What are the 3 critical factors which must be monitored continuously in an aquatic system?
Temperature, water level, and power failure
Biofilters can te re-seeded after disinfection by placing them into a well-established reserve system. What are 2 ways the biofilters can be fed in the reserve system?
The first is to have resident fish or invertebrates that can provide waste material to feed the bacteria. This can potentially harbor reservoirs of infection. The second is to release ammonia into the system on a periodic or continuous basis.
Is “topping off” or the practice of adding water to compensate for evaporative losses equivalent to conducting water changes?
No, toxic compounds do not evaporate at the same rate as water and will accumulate in the water.
What is the recommended percentage of water to change out of a tank without harming the fish?
0.75-1.0%/day - small frequent changes reduces the impact of temperature, pH, ionic, or other shocks that may occur 25-50% water change at one time may be used if the water is properly conditioned & may be useful to manage disease
Are diets fed to laboratory fish complete for optimal growth?
Probably not. Empirically derived diets are usually relatively unrefined. Trace nutrient balance is rarely considered and quality control, including component selection for diets, is minimal. Relatively little is known about the natural diets of many commonly kept fish or about the effects of trace imbalances on fish physiology.
What are some important considerations when housing multiple species of fish in a primary enclosure?
Schooling, size differences, time-in-residence territoriality, gender interactions, and other social complexities
What is the best method to ensure fish are disease free before starting research?
On-site screening at the source can reduce the probability of introducing disease into laboratory water systems but these suppliers are rare. Alternatively fish can be quarantined and screened in-house.
What is an appropriate quarantine period?
14-21 days for many problems, but 4-6 weeks is recommended for concerns about mycobacterial infections.
