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Check out the ich on the top fin on this foot-long pacú.

Most Common Disease.  Ich ranks number one on the disease hit parade.  It’s easy to get.  A little chill is all it takes.  Chilling interrupts slime production – the fishes’ main defense against diseases.  Other stressors will also help ich parasites sink their teeth into your fish.  Happily, it’s also easy to cure ich if you treat it early.

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You can see ich spots on this little P. sutchi.

External Signs.  Look for white spots that look like grains of salt, clamped fins, and sometimes slimy skin.

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Severums get ich, also.

Behavior:  Beware if your fishes exhibit listlessness, loss of appetite, hiding, lying on the bottom, and/or scraping on the bottom or other objects.  Many of these symptoms show up before the tell-tale white spots.

Ich kills.  If left untreated, ich will probably kill most of your fishes.  Each tiny white spot represents a parasite living under the fishes’ skin and sucking a little blood.  A few parasites don’t really hurt much.  However, if left untreated, each tiny white spot drops to the bottom and multiplies into exactly 1,024 baby bloodsuckers within 24 hours – a real population explosion.

Stress Weakens Fish.  Ich germs live in most tanks in small quantities.  Healthy fishes ward them off easily.  However, poor water quality and stress – particularly chilling – make your fishes susceptible to invasion by ich. 

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Ich spots often show up first on their pectoral fins.

Main Cause of Ich.  Most ich starts when your fishes get chilled.  But other stress factors cause ich also:  overheating, fright, too much light, no hiding places, bullies, too many fishes in the tank, poor water quality, ammonia, nitrite, low oxygen, insufficient aeration or filtration, overfeeding, water too hard or too soft, too much fresh tap water.

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This 18-inch fire eel stressed out in a tank of large fish and now has ich.

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Even goldfish can catch ich.

Beware Cold Weather:  Chilling interrupts the fishes’ slime production process – his main protection against disease.  The opportunistic ich parasites burrow under the fishes' skin and start sucking out blood and other fish juices.  Your fish tries to protect itself by growing a covering over the invaders – hence the characteristic white spot.  You can’t kill an ich parasite while it’s entrenched under the fishes skin.  And you can’t scrape them off.

Adult Ichs Encyst:  In three to five days, the ich organism gets its fill of fish juice and drops to the bottom of the tank.  On the bottom of your tank, the ich develops a very heavy wall or cyst and becomes virtually invulnerable for about 24 hours.

Baby Ichs Are Vulnerable.  During this 24-hour period, the mature ich divides once, twice… exactly ten times and grows into exactly 1,024 ich swarmers which burst from their cyst and start looking for fresh fish flesh and fluids.  At this stage, nearly anything kills the little swarmers.

Effective Medications:  Malachite green, formalin, quinine hydrochloride, and copper all work.  A combination of malachite green and formalin works best.

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Synodontis with a royal case of ich.

The Other Medication.  Sensitive (scaleless) fishes such as fire eels, elephant noses, and pictus cats are very sensitive to malachite green.  Use quinine hydrochloride when in doubt.

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Even foot-long catfishes get ich.  Careful with your med.

Medication Comments:  Medications are poisons – hopefully strong enough to kill the disease organisms without killing the host organism.  An overdose of the cure will often kill your fishes.  Use medications carefully.  Use ich treatments at half strength for baby fish, scaleless fish, weak fish, and tetras.

Parasite-Killing Foods.  Tetra makes a food (or used to) that helps kill parasites of the fishes that eat it.  Unfortunately many sick fishes lose their appetites.  Also, the treatment usually takes 10 days – much longer than the standard ich remedies.

Other Hitchhikers.  Other protozoan organisms often invade your fish along with ich.  Conditions that make him susceptible to ich invasion also make him a happy campsite for other unwelcome campers.  Trichodina, oodinium, and costia usually come along for the ride. Most ich remedies also kill them at the same time.  Treat for five days to make sure.

After the Invasion.  Ich and other protozoans punch holes in the fishes’ skin.  Bacteria find these open places an excellent place to set up camp.  Correct your water conditions to help the fish regenerate his protective slime coating.  A squirt of Novaqua also helps.  Really bad wounds also invite saprolegnia – an underwater fungus that grows on dead tissue. 

Microscopic Note.  Under magnification, ich cells show an easily identified horse-shoe shaped nucleus.  This makes ich very easy to identify.

Easy Prevention:  Aim for a stable temperature, regular water changes, varied diet, compatible tank mates, one teaspoon of salt per gallon, a good filtration system, and add a standard ich treatment at half strength for the first three days after you add  new fishes to your tank.

Five-Day Life Cycle Tips:  Adult ich parasites reproduce in about five days at 80^o.  Always treat for five days.   Most ich invaders die after 55 hours in a tank without fish.  Siphoning the bottom removes the encysted adults before they multiply into baby bloodsuckers.  Very strong aeration prevents the adults from encysting and reproducing.  Higher temperatures make ich run through its life cycle faster.

Diatom Filters:  Filters that use diatomaceous earth as the filter media remove organisms as small as one micron.  That means they filter out the mature ich cells that drop off your fish before they encyst.

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Ich spots cover this flower horn cichlid's back and top and bottom fins.

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Ich can kill the little guys.

Prevent Ich:  Put all new fishes in a quarantine tank for one to two weeks.  Good quality water and minimal stress helps healthy fishes ward off ich and other infestations without medications.  Quarantine tanks make sure you won’t introduce unwanted invaders into your tank.  LA

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