A pet store I work at has been having issues with marine fish. The tank system has been running for a month, but all fish that are received decline in health in a strange way. For a couple of days they'll appear fine, but then have trouble swimming straight. They seem dizzy, and stop using their tails, as if their back half is paralyzed, then will rest on the substrate for about a day before passing on. It is a slowly progressing ailment, taking about 4 days for chromis, to a week for a valentini puffer to die. They retain their colour until just a few hours before death, and breathing rate increases over time until death. If I suspect a fish will not make it through the night, I buy it, and once out of the store tanks, they improve. For instance, a domino damsel was on death's door, pale and unmoving besides its gills. 4 days later in my tank it is swimming mostly upright and accepting food, though not using it's tail much yet. Yesterday I took home a bicolour blenny that I could have sworn was dead in the bag, this morning it is alert, fully-coloured, and occasionally moving.
It seems to me that there is a toxin of some kind in the store tanks that builds up within the fish while exposed. I have done a 30% water change, which may have slowed the progression of the ailment, but the issue clearly remains. The thin layer of sand used in the tanks was collected from a nearby beach, and I noticed a smaller-grained sparkling black sand settling atop the regular pale sand. Is it possible for it to be something like a sulfate mineral leaching metals into the water? Otherwise, I am at a loss. I will continue to do water changes and see about replacing the sand, but I would love to have some insight on this issue.
Fish affected: Blue chromis, Yellowtail damsels, Domino damsels, Humbug damsels, GHS gobies, Bicolour blennies, Yellow clown gobies, Pyjama cardinals, Valentini puffers, Falco hawkfish, Fire gobies
Parameters of store tanks
Fish only
Sump with filter sock and bioballs, plus a purge system which is switched off (as it would automatically refill with fresh tap water)
UV steriliser
Volume: 400 litres in total
Salinity: 1.021
pH: 8.2
Temp: 25C
Ammonia: 0
Nitrite: 0
Nitrate: 0
Phos: 0
I don't currently have access to more test kits than that.
Water was initially mixed in the tanks, not transferred from a bucket that could have leached chemicals into the water. Salt used is Aquasonic Ocean Salt, which I have been using in my home tank where the fish are recovering. Tap water is filtered (I think by RO? Not sure, exactly) before it pumps into the tanks as automatic top-off, the same with all the freshwater setups which have no such issues. There are aquarium ornaments in the tanks too, but I haven't had a good look at what they're made of. I dose Aquasonic Power and Protech at the recommended dosages.
It seems to me that there is a toxin of some kind in the store tanks that builds up within the fish while exposed. I have done a 30% water change, which may have slowed the progression of the ailment, but the issue clearly remains. The thin layer of sand used in the tanks was collected from a nearby beach, and I noticed a smaller-grained sparkling black sand settling atop the regular pale sand. Is it possible for it to be something like a sulfate mineral leaching metals into the water? Otherwise, I am at a loss. I will continue to do water changes and see about replacing the sand, but I would love to have some insight on this issue.
Fish affected: Blue chromis, Yellowtail damsels, Domino damsels, Humbug damsels, GHS gobies, Bicolour blennies, Yellow clown gobies, Pyjama cardinals, Valentini puffers, Falco hawkfish, Fire gobies
Parameters of store tanks
Fish only
Sump with filter sock and bioballs, plus a purge system which is switched off (as it would automatically refill with fresh tap water)
UV steriliser
Volume: 400 litres in total
Salinity: 1.021
pH: 8.2
Temp: 25C
Ammonia: 0
Nitrite: 0
Nitrate: 0
Phos: 0
I don't currently have access to more test kits than that.
Water was initially mixed in the tanks, not transferred from a bucket that could have leached chemicals into the water. Salt used is Aquasonic Ocean Salt, which I have been using in my home tank where the fish are recovering. Tap water is filtered (I think by RO? Not sure, exactly) before it pumps into the tanks as automatic top-off, the same with all the freshwater setups which have no such issues. There are aquarium ornaments in the tanks too, but I haven't had a good look at what they're made of. I dose Aquasonic Power and Protech at the recommended dosages.