Some fish are particularly sensitive about the temperature of the water they are living in. While most fish can handle temperatures that vary by 8-10 degrees, others are only comfortable at a certain temperature or temperatures very close to their ideal. It means adding a heater or two or finding a better, cooler location for your fish tank. In addition, fish that are sensitive to temperature also tend to be very sensitive to water conditions and may require more care and tending than fish that are hardier. Such examples include…
Rabbitfish – There are only a few types of Rabbitfish common in the aquarium trade, the one-spot foxface, the barhead, and the goldlined. Rabbitfish are herbivores that graze solely on vegetation, which means that they need a steady supply of algae, other vegetable matter such as boiled lettuce or spinach, and flake food. They should be able to graze freely throughout the day. They require high water quality and should be kept in a tank with a stable pH of 8.3 and temperatures at 78˚F. In addition, high quality filtration is necessary to keep nitrates and ammonia at low levels.
Puffers – Keeping Puffers can be a bit of a challenge and is a huge undertaking for a fish owner. Be careful adding them to your tank as they can accidently poison your entire system. Remember to handle them with care because they can sting. They are generally peaceful, however, and will leave most companions alone. They have a hardy carnivorous appetite and enjoy fish meat, shrimp meat, brine shrimp, and flake foods. They should be fed a couple times a day. Their tank requirements are fairly strict. They require a pH between 8.1-8.3 and temperatures between 77-79˚F. In addition, you must be sure you do a 15-25% water change every 10-14 days to make sure that the water stays clean enough to support your puffers.
Betta/ Siamese Fighting Fish – Known for their vibrant colors and lovely, flowing fins, Bettas are highly sought after fish. They are labyrinth fish, which means they have a special organ at the top of their head that allows them to breathe oxygen from the air outside of their water in addition to the oxygen dissolved in their water. Though they can withstand a large range of temperatures, a well-kept Betta is kept in water about 80˚F. Anything less than this and they will begin to become listless and lose energy. Bettas should ideally be fed insect larvae, but they can also tolerate flake foods if necessary.
Oscars – Oscars are relatively hardy and easy to care for, however they should be kept in water between 76-80˚F. They grow very quickly when well cared for and will outgrow a 30 gallon tank easily within a year. They are quite peaceful, but they should not be kept with fish that are significantly smaller as they will simply eat anything small enough to fit into their mouths. They are hardy eaters and if your Oscar is not showing a good appetite then it is probably ill and should be taken to a veterinarian.