Fish are affected by temperature, so if it's too hot or too cold, they could die.
Regarding temperature:
The ideal temperature for a marine tropical fish aquarium is 78-82 degrees Fahrenheit. The ideal temperature for a reef aquarium is 75-78 degrees Fahrenheit.
Regarding specific gravity (salinity):
Saltwater aquariums are usually maintained at a S.G. of 1.020-1.026, depending on the type of organisms maintained in the aquarium. Reef aquariums or any aquarium housing invertebrates generally needs a higher S.G., while aquariums housing only marine fish are best maintained at a slightly lower S.G.
Regarding pH:
The ideal pH for a marine aquarium is 8.1-8.4. Excess fish food and waste, biological filtration, tap water, the decay of algae, bacteria and other organic compounds all contribute to the decline of pH levels in the marine aquarium. |