First Aid Treatment
A dead fish in the pond is not just bad news -
it usually means there are worse news on the way. A koi
doesn't usually just turn up dead in the pond. It is more
likely to be a victim of poor water quality, inadequate oxygenation,
disease invasion, or a combination of the above. Regardless of
the cause of death, you can be sure that there are other koi
affected. Seeing a dead fish in the pond should therefore
trigger you to act decisively and swiftly to prevent the death of
First aid treatment of affected koi can
not happen unless the pond owner recognizes the tell-tale signs of
an impending problem. Fish gasping at the surface of the water
indicates that the dissolved oxygen in the pond is inadequate for
the fish population. Immediately subject the pond to aeration
to rectify the problem. Aerators and bubblers are the proper
equipment for this purpose, but agitating the surface of the water
will help if none of these equipment is available. Making the
water returning to the pond from the filter splash onto the pond
surface will create ripples that greatly promote oxygenation of the
A change in the appetite of the koi is also an
indication of a health problem. Koi have big appetites, so you
should become suspicious if they're not taking in those pellets as
voraciously as they normally do. Other
signs of health
problems that can't be ignored are: 1) sluggish or erratic
movement; 2) strange position in the water; 3) labored
breathing; 4) folding of the pectoral fins to the sides; 5)
parasites or spots anywhere on the koi; 6) blood-streaked fins; 7)
bloated abdomen; 8) discoloration; 9) popped eyes; 10) raised
scales; and, of course, 11) lesions or ulcers on the fish.
The first thing you should do if you
spot any of these symptoms is to check the pond's water quality.
Extreme ammonia, nitrite, or pH readings would necessitate an
immediate 50% water change. Some koi experts recommend
boosting the pond's salt content to 0.5% to relax the koi until they
recover. Note, however, that there also koi experts out there
who'd never subject their koi to salt. Salt has some
bactericidal properties, so this practice has merits of its own.
Net out the affected koi and isolate them from
the main population. Examine these sick koi for lesions.
Lesions may be treated with potassium permanganate using a cotton
swab. Iodine may also be used as a substitute. Be sure
to keep all medicines away from the gills.
Figure 1. Sick koi
must be netted out
of the pond and inspected for
Check the sick koi for parasites as well.
Most parasites can be destroyed by salt, so this is another reason
why quarantine tanks are usually kept with a salt concentration of
0.5%. Some parasites need special chemicals to be eradicated.
You may therefore need to call in your vet if you're not sure what
your fish is infested with.
Hospitalize your sick koi in the quarantine
tank until they are totally cured before putting them back into your
main pond. Feed your sick koi premium koi pellets and natural
food (such as shrimps and fruits) to hasten their recovery.
They should likewise be kept in properly-oxygenated and comfortably
warm water (76-82 deg F) while under quarantine.