THINGS THAT WILL
eunicid worms (head has distinct tentacles)
crabs---(any crab with a large claw)
ich (is a parasite, operating much like fleas) and is not 'caused' by anything but its natural reproductive cycle. If it gets into your sandbed, 72 days of no fish is your treatment for the tank.
uronema marinum---particularly on chromis---red ulcers and white film: a disease. Add in brook, most found on clownfish; and flukes; all this is why you quarantine these wildcaught fish who've been through too much togetherness during the collection and sales process.
low alkalinity. Keep it between 7.9 and 9.0, generally. If your alkalinity drops and can't be raised, your magnesium level is low. This isn't in itself fatal, but leads to loss of slime coat and vulnerability to disease and parasites the fish might have resisted.
low oxygen: any time your fish are near the surface persistently, oxygen levels should be a thought. Providers of oxygen: your skimmer, particularly a good one; your return pump, particularly if the water has to fall, causing bubbles; cheato moss in the sump; and an ADEQUATE, surface-stirring agitation---aim a powerhead at the water surface, for one thing.
venomous or spike-armed roommates, especially if the tank is too small. In this case stress IS the culprit---on the armed roommate, who will lash out in distress and lower the tank population.
stray current: a cracked heater or other electric device sending current through the water. Leaves no mark: otherwise healthy fish die.
some snails: if you have fish that sleep in the sand and you black out the tank completely, they may eat the fish alive. Nassarius are particularly bad about this. The takeaway is---don't black out your tank.
Coral-banded shrimp and green serpent stars, also sally lightfoot crabs may take after fish, particularly those that sleep on or in the sand, or that move slowly. Fuzzy large mushrooms can also kill fish by suffocation: they close up like anemones.
Too fast a salinity RISE.
A powerout over the capacity of your tank to provide oxygen: warmth is not a concern, but oxygen is. Consider a battery-driven Penn-Plax pump that will aerate automatically if your area is prone to power loss.
Failure to test basic parameters. Not knowing your temperature, salinity, alkalinity is critical. And for stony reefs, clams, etc, that have stony parts, also your calcium and magnesium levels.
A decision to add whiz-bang supplements without testing the levels. In general adding anything BUT alkalinity buffer, and calcium, and magnesium (for a reef) is not a good idea for a novice; and it's generally not a good idea for an expert. Test to know your levels before dosing ANYTHING, and wait 8 hours before testing AFTER dosing.
Too long an acclimation for a shipped fish; or acclimation in general if mishandled: read the sticky.
A nephew who puts a tv remote or toy truck into your tank: run PolyFilter and a bag of carbon in your water stream, and if it's Cheerios, start doing a 30% water change followed in two days by a 20%. That will usually get you out of it. If a guest knocked a martini into your tank, the worst you'll usually get is a bacterial bloom and a lot of skimmate.
These are most of the hazards.
THINGS THAT WON'T [but look scary.]
Things that are often of concern, that WON'T kill your fish:
bristleworms: some fish take a few tries to learn---but the spines do fall off harmlessly after several days.
kalk overdose (rarely harmful)---do check your salinity, however, as it IS fresh water.
4 days starvation: most fish can forage, and if you have to go out of town, either have a sitter you can trust, an AUTOFEEDER, or don't feed. A pity-feeder who does not understand the danger can harm your tank. Also to watch---if you have cranky fish that might take after weaker ones, you need an autofeeder: Eheim makes a real good one, good for flake or pellet and will feed multiple times a day.
a topoff accident: fish can stand a DROP in salinity. To raise it back to normal safely, just topoff with salt water instead of fresh. If you have a reef, there are other considerations, but corals usually just expell 'wrong' water and wait for conditions to improve.
a few days without a skimmer/a week or so without a water change --- because---life, is all.
eunicid worms (head has distinct tentacles)
crabs---(any crab with a large claw)
ich (is a parasite, operating much like fleas) and is not 'caused' by anything but its natural reproductive cycle. If it gets into your sandbed, 72 days of no fish is your treatment for the tank.
uronema marinum---particularly on chromis---red ulcers and white film: a disease. Add in brook, most found on clownfish; and flukes; all this is why you quarantine these wildcaught fish who've been through too much togetherness during the collection and sales process.
low alkalinity. Keep it between 7.9 and 9.0, generally. If your alkalinity drops and can't be raised, your magnesium level is low. This isn't in itself fatal, but leads to loss of slime coat and vulnerability to disease and parasites the fish might have resisted.
low oxygen: any time your fish are near the surface persistently, oxygen levels should be a thought. Providers of oxygen: your skimmer, particularly a good one; your return pump, particularly if the water has to fall, causing bubbles; cheato moss in the sump; and an ADEQUATE, surface-stirring agitation---aim a powerhead at the water surface, for one thing.
venomous or spike-armed roommates, especially if the tank is too small. In this case stress IS the culprit---on the armed roommate, who will lash out in distress and lower the tank population.
stray current: a cracked heater or other electric device sending current through the water. Leaves no mark: otherwise healthy fish die.
some snails: if you have fish that sleep in the sand and you black out the tank completely, they may eat the fish alive. Nassarius are particularly bad about this. The takeaway is---don't black out your tank.
Coral-banded shrimp and green serpent stars, also sally lightfoot crabs may take after fish, particularly those that sleep on or in the sand, or that move slowly. Fuzzy large mushrooms can also kill fish by suffocation: they close up like anemones.
Too fast a salinity RISE.
A powerout over the capacity of your tank to provide oxygen: warmth is not a concern, but oxygen is. Consider a battery-driven Penn-Plax pump that will aerate automatically if your area is prone to power loss.
Failure to test basic parameters. Not knowing your temperature, salinity, alkalinity is critical. And for stony reefs, clams, etc, that have stony parts, also your calcium and magnesium levels.
A decision to add whiz-bang supplements without testing the levels. In general adding anything BUT alkalinity buffer, and calcium, and magnesium (for a reef) is not a good idea for a novice; and it's generally not a good idea for an expert. Test to know your levels before dosing ANYTHING, and wait 8 hours before testing AFTER dosing.
Too long an acclimation for a shipped fish; or acclimation in general if mishandled: read the sticky.
A nephew who puts a tv remote or toy truck into your tank: run PolyFilter and a bag of carbon in your water stream, and if it's Cheerios, start doing a 30% water change followed in two days by a 20%. That will usually get you out of it. If a guest knocked a martini into your tank, the worst you'll usually get is a bacterial bloom and a lot of skimmate.
These are most of the hazards.
THINGS THAT WON'T [but look scary.]
Things that are often of concern, that WON'T kill your fish:
bristleworms: some fish take a few tries to learn---but the spines do fall off harmlessly after several days.
kalk overdose (rarely harmful)---do check your salinity, however, as it IS fresh water.
4 days starvation: most fish can forage, and if you have to go out of town, either have a sitter you can trust, an AUTOFEEDER, or don't feed. A pity-feeder who does not understand the danger can harm your tank. Also to watch---if you have cranky fish that might take after weaker ones, you need an autofeeder: Eheim makes a real good one, good for flake or pellet and will feed multiple times a day.
a topoff accident: fish can stand a DROP in salinity. To raise it back to normal safely, just topoff with salt water instead of fresh. If you have a reef, there are other considerations, but corals usually just expell 'wrong' water and wait for conditions to improve.
a few days without a skimmer/a week or so without a water change --- because---life, is all.
Last edited:
