1. water quality.
salinity 1.024, alkalinity 8.3, and if you have corals---calcium 420, magnesium 1350; temperature around 79-80.
2. lack of tests. Buy a refractometer and a NUMERICAL set of tests. Sorta-pink is not a helpful answer to 'what is your alkalinity?' If you don't test, you don't know what's going on . And use these things BEFORE you get a fish or coral.
3. buying sick fish. Do not pity-buy unless you have a spare tank to devote to your rescue for at least several months. Buy the oneriest, pushiest, fattest fish with impeccable finnage, the one the others are afraid of. Not the poor little fellow hovering in the corner, and be particular. Pick. Don't leave it to the store. [And the other fish will thank you for removing the bully.]
4. Have enough live rock and don't rush the cycle. 4 weeks of CUC only will mature your sandbed into something far more useful. End of cycle is not a signal to dump 10 unresearched fish into a new tank. Go slow!
5. Google the fish before buying. Just because it's shiny-new in the store doesn't mean it's the last they'll ever have. Most stores will try to get you one too, once you know it really is going to do well in your tank.
6. ask other owners about the fish's habits. Wrasses may sleep in the sand. Filefish may sleep nose-down. Many gobies dig, some more than others. Blennies can starve without green food. 'Dory' maxes at 10" to a foot in length and does NOT adjust her size to the tank she's in. Chromis assassinate the weakest of their number until they fit the tank. If ever. Certain fish hate other fish. Ask. Don't accidentally buy a food chain.
salinity 1.024, alkalinity 8.3, and if you have corals---calcium 420, magnesium 1350; temperature around 79-80.
2. lack of tests. Buy a refractometer and a NUMERICAL set of tests. Sorta-pink is not a helpful answer to 'what is your alkalinity?' If you don't test, you don't know what's going on . And use these things BEFORE you get a fish or coral.
3. buying sick fish. Do not pity-buy unless you have a spare tank to devote to your rescue for at least several months. Buy the oneriest, pushiest, fattest fish with impeccable finnage, the one the others are afraid of. Not the poor little fellow hovering in the corner, and be particular. Pick. Don't leave it to the store. [And the other fish will thank you for removing the bully.]
4. Have enough live rock and don't rush the cycle. 4 weeks of CUC only will mature your sandbed into something far more useful. End of cycle is not a signal to dump 10 unresearched fish into a new tank. Go slow!
5. Google the fish before buying. Just because it's shiny-new in the store doesn't mean it's the last they'll ever have. Most stores will try to get you one too, once you know it really is going to do well in your tank.
6. ask other owners about the fish's habits. Wrasses may sleep in the sand. Filefish may sleep nose-down. Many gobies dig, some more than others. Blennies can starve without green food. 'Dory' maxes at 10" to a foot in length and does NOT adjust her size to the tank she's in. Chromis assassinate the weakest of their number until they fit the tank. If ever. Certain fish hate other fish. Ask. Don't accidentally buy a food chain.