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There are a wide variety of test methods available; a description of a possible water quality testing kit for fish veterinarians is provided in Box A2.2. Commercial test kits are available from various distributors (e.g. API, CHEMetrics, Hach, Seachem, Tetra). Handheld or system‐mounted meters are available from various commercial suppliers (e.g. Fisher Scientific, Hach, LaMotte, Oxyguard International, Pentair, YSI Inc.). Some methods, such as spectrophotometry, high‐performance liquid chromatography, and ion‐exchange chromatography may be limited to zoo and aquarium laboratories, and commercial, state, or federal aquatic animal health laboratories; the assays may be available to the public.

Factors to consider when selecting water quality test methods include accuracy, sensitivity (detection limits), calibration and maintenance requirements, ease of use, cost of purchase and maintenance, durability, reliability in working conditions, and associated disposal requirements (e.g. reagents).

When building a water quality testing program for an institution or practice, it is helpful to start with target ranges for each of the systems (based on the needs of the species and the life support equipment used), the expected ranges for the source water, and targets for disposal of the discharge water. This can be followed by a risk assessment of the most likely issues:

 Source water (e.g. low dissolved oxygen, inappropriate temperature, incorrect composition of salt mixes, high chlorines in municipal water, high iron in well water).

 System water (e.g. high nitrogenous wastes, pH change in low‐pH systems, temperature change in tropical fish systems, oxidative by‐products and low iodide in systems with ozone disinfection, drug assays). It may be useful to divide systems based on age (e.g. newly established/newly stocked versus stable) or use (e.g. quarantine systems).Box A2.2 Minimum Water Quality Testing KitThermometer for temperatureRefractometer or conductivity meter for salinityColorimetric tests for ammonia, nitrite, nitrate, alkalinity, copper, chlorine, +/‐ calcium, phosphate, iodidepH meterDissolved oxygen meter+/− Total gas pressure meter

 Discharge water (e.g. drug residues, temperature, salinity, pathogen load).

 Transport water (e.g. low dissolved oxygen, high ammonia, inappropriate temperature).

Consideration can also be given to potential research topics. These analyses can be used to guide decisions on type of testing, frequency of testing, and hardware, space, and staffing requirements.