The correct care of Zebrafish is essential to maintain their health and well-being as suitable specimens for pharmaceutical research and development. This freshwater fish is an important alternative model and good husbandry delivers successful scientific results. Read on to learn how Zebrafish research is fueled by proper zebrafish care.
How are Zebrafish cared for?
Zebrafish are an easy to care for inexpensive breed that reproduces in large numbers. This makes them commonly used as an alternative model to animal testing.
Reputable laboratories that use Zebrafish for testing adhere to the highest husbandry standards and work within the 3Rs policy which is:
In terms of Zebrafish care, refinement is the key to how Zebrafish are kept and refers to their well-being to ensure they are treated humanely.
Zebrafish are an active species and are kept in tanks with a large surface area, allowing them plenty of room to swim. Due to their popularity as an alternative model, some laboratories hold hundreds of tanks full of thousands of fish, ensuring they have adequate space to move.
These tanks are usually made of polycarbonate, acrylic or glass and have a cover, as Zebrafish are prone to leaping out of the water.
Their natural habitat is replicated as close as possible in breeding programs, by the use of filter pumps and tall plants. The plants give the fish a place to hide from any aggressive models that may be in the tank.
Zebrafish tend to live near the surface of the water, near the light as light encourages them to breed. However, periods of rest are important too, and Zebrafish care includes the dimming and brightening of artificial light to prompt breeding.
Water temperature and quality
The quality of the water used by laboratories to care for Zebrafish is paramount. Good quality water results in the correct conditions for successful breeding.
Whilst Zebrafish are known to be adaptable and are able to withstand wide temperature ranges (between 6°C - 38°C) when used for research it is advised they are kept at 28.5°C. This allows for adequate growth and breeding.
The pH level of the water is maintained at 7.0 – 8.0 and is tested regularly. Most laboratories use deionized or distilled water as tap water can often be too hard, due to it containing high levels of calcium or excess fluoride.
The water is replaced regularly with a supply of water that maintains the same temperature as the tank to avoid shock. A common water-changing method is the use of drip-through systems, which supply new water and drain away the excess, dirty water.
As an alternative to this system, some laboratories use a manual water replacement method, which removes debris from the bottom of the tank and replaces it with clean water.
Laboratories tend to feed Zebrafish with a combination of live and dried food to provide a balanced diet. Food especially developed for Zebrafish is advised for a healthy diet and to achieve high-quality testing results. Feeding is carried out depending on the age of the fish and is usually 2-3 times per day as they are growing. More frequent feeding may be appropriate for the fish larvae, depending on the experiment to be carried out.
Feeding is either done manually or with automatic feeders.
Zebrafish feeding is carefully monitored and recorded, so laboratory staff are aware of the correct regime and testing program for the fish in each tank.
Equipment cleaning and care
To maintain high standards of husbandry, tanks, filters and equipment are kept clean using the recommended cleaners.
The cleaning system is determined by the number of fish being stored, the tank material, the type of water and the feeding regime.
Contamination can easily occur through equipment such as nets, therefore anything the Zebrafish may come into contact with must be correctly sanitized. Staff wear gloves and follow regular handwashing procedures when Zebrafish breeding, to prevent contamination.
Cleaning is carried out in such a way as to minimize any stress to the Zebrafish.
In summary, the care of Zebrafish in laboratories follows a structured and formal procedure that complies with the relevant protocols to ensure the safe husbandry of the fish and to achieve the best possible results for research and development.