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i have a 90 gal tank,48"x20"x24".i have asorted cichlids in it.it is a well established tank over 2yrs.i have not added anything new.i have not changed foods.i have checked water peramiters they are all fine.and the fish all get along well.and i do water changes regularly.now here is the problem.i have had 5 fish die in the last 3 weeks including one bristle nose pleco.and i can find no reason why,they have no physical marks to indicate any problems.they look very healthy.but i have noticed before they have died(night before)that they have been out of sorts.example my venus hap is always out showing off and patroling the tank.but the night before he died he was hidden in behind some rocks an a plant not moving.another example my cherry fin same thing always out showing off,then next day hidden aswell.about 2hours later i put my hand in tank to check him .he moved only when i touched him,normaly my fish swim away when i get near them.10 min later he is thrashing like a fish on a hook at the top of the tank for about 10 to 15 seconds.then just stopped suddenly and was dead. i have checked each fish that has died.and can find no signs of fungus or any other disorders that would kill them.i have tried to be as detailed as possable,because this is a mystery to me.and i am hopeing someone can shed some light on this for me.so i can try to stop it before more of my fish die. any thought or coments on this would be great thank you.

If the water quality is truly fine, then the cause must be something else, but it would help if you gave the actual readings, it can help to indicate a lot of problems whether you regard them fine or not, we keep saying it. You also didnt mention anything about the average tank temperatures or their stability, and that might be worth checking too.I would also mention the specific species you keep, as there may be water hardness compatability isuues. Some fish tolerate the wrong hardness for years, then finally upsticks and die. If any of the fish were wild caught and from diffent systems than the other fish, that can also have disease resistance complications.

Assuming the water quality is really ok, and there have been no new fish etc, the things I would begin investigating are those conditions that can be present for years with no noticeable sign, and by this I mean the internal parasites. This includes roundworm, tapeworm, pinworm, and flagellate protozoa. They build slowly and start eventually killing fish, often with no symptoms.Other issues might be dietary. What do you feed your fish?

This may sound gross but it might be worth having a look at the contents of the stomachs and intestines of the dead fish. Obviously look for worms , and other things heavily mineralised organs or lots of enlarged yellow fatty tissues.Sometimes the parasites are not always visible, as is the case with protozoans, but the gut and intestines sometimes show a lack of digested or partially digested foods. Sometimes, if you got to a fish within minutes of death, and open up the stomach, look for abnormally rapid decomposition gaseous bloating in the stomach and a foul smell, and that will often indicate bacterial causes.


Without more info, if I had to give a guess diagnosis, and given the range of species affected, and the manner of their deaths, and the stable pre-existing stability of the tank, id say the odds on cause was flagellate protozoa.

Might be worth getting some jungle labs anti- parasite formula , and see how it goes.

thanx for the reply
more info
water changes of 30 percent 3 times amonth some times only twice.
ph is at 8
average temp is between 78 and 80
and no amonia or nitrite detected.
i feed my fish a huge asortment of foods,from shrimp pellets,veggie flake food,cichlid sticks,and floating pellets.
and they have there treats aswell.krill and earth worms and sometimes insects.
my fish look very healthy and happy that is whats puzzling me.
aslo i have checked fish after death.no smell and nothing i could see inside the stomach.but my female venus haps did have eggs.
here is a picture of tank set up before any fish died.

http://www1.snapfish.com/slideshow/AlbumID=143539919/PictureID=2902387949/a=89683185_89683185/t_=89683185

oh and last fish itroduced to tank was about 6 months ago it was 4 yellow labs.from another tank i have(i have 5 tanks)and i have had no fatalities in any other tanks.hope this helps to find an answer
thanks

Thats pretty much it then, the bugs and worms in the diet are bringing in the protozoan parasites and parasitic worms in. Give all the fish a general treatment like the aforementioned jungle labs stuff. When fish are gravid, they are under tougher metabolic demands, and with a protozoan infection too, the result can be blood anaemia.

Time for a bit of general delousing. Nice tank btw

thanx again for the info
before i start medicating,is there anyway to test for these parasites? i don't like putting chems in my tanks unless it apsolutly nessasary.
the insects i feed are store bought and are freeze dried.
and the earth worms are left over from summer time fishing.
i didn't realize earth worms could carry parasites.i won't feed them worms anymore or insects just to be safe.my fish will be sad
is there any other possabilitys that could be causing my fish deaths?
thanks again

Unless you have a microscope and know what to look for in terms of protozoa or worm eggs from either faecal samples or a post mortem corpse there will be no obvious external signs in many cases.

If the water quality is really a-ok, with no evidence of toxins, then biological causes like disease or parasitism are really the only other options remaining. Presumably if there was territorial violence , youd see signs of injury.

I really dont see any other option than treating the fish, unless you really wanted to gamble on not losing more.Id rather take a risk on a fairly safe treatment for internal parasites than risk further deaths.

thank you longhairedgit.
i will give it a try.
i will keep you posted.

update

hey longhairedgit
i went to my lfs to look for the meds you mentioned
the jungle lab for internal parasites.also took samples of my tank water for testing,just incase i was doing my testing wrong.
the test results where same as mine.
ammonia-0
nitrate-10ppm
nitrite-0
ph-8.0
also the temp of the tank is set at 80
i have increased water changes,i did a 35% water change and then aprox 10% daily for a week.
the lfs has not heard of jungle lab.but said all i needed was salt.since the meds were not avalable i took there advice and added salt as directed 5ml for every 10 gal to treat for parasites and with every water change.now im not sure if it was the salt or whatever it was that was killing my fish had run its coarse,but i have had no more deaths
i am not convinced it was the salt though.i was reading another post you replyied to similair to mine.and you had mentioned other toxins in the water that would not show on a reading.eg hair gel, scented candles etc.i do use hair gel but i wash my hands.
this leads me to another question.i have put unpeeled zuccini and peas in my tank,i did lightly rince them though.could these have polluted the water maybe.
also if it was the salt that helped should i still add salt at my water changes and for how long.
the remaining fish in the tank are:
4 yellow labs
1 rino pleco
1 bristle nose pleco
1 Tropheus duboisi
1 Quetzal Cichlid
at any rate i am glad my fish are not dying anymore.
let me know what you think.
thanks lhg

michael

A few of the less virulemt strains of bacteria etc,can be killed with a little aquarium salt, but if any of the bacteria survive they may well readjust to the new slightly higher salinity. Obviously the cichlids you have can only tolerate so much salt, so if the same problems flare up again, then p[erhaps choose an antibacterial med over hiking up the salt levels.

TBH it depends where you got your zucchini from, I know its usual for pyrethrin based pasticides to be used, and they cant really be washed off,they penetrate throughout the food but you can reduce the toxicity by blanching veggies before you put them in the tank. Some countries that are not well regulated still used DDT based pesticides though, and they can be lethal to fish, and this you can peel off.Usually you have to peel off at least 5mm depth to be sure of getting most of it.

Glad theres no more deaths, keep a close eye for a few weeks to be sure, and go for meds like maracyn if things flare up again. Salt doesnt always work forever, and using it for extended periods usually does nothing, so take the advantage of stopping it after two weeks or so, so that you can use it again as a first line defence should the problem come back. Bacteria will colonise a tank eventually whatever the salinity, its the sudden change that kills them, not the presence of the salt itself. In the back of my mind im still thinking the cause was probably bacterial.Hopefully you nailed the bugs first time though.

Its also possible that losing fish may have been connected to a water hardness issue too,, and the salt will have hardened the water up for you a little. Should you need to hike the hardness though theres other ways than using salt though. I like crushed oystershell myself.

Congrats on no further losses.

Good luck!

once again thanks LHG.
i will stop with the salt after next water change.and i will keep an eye out for the jungle lab meds or an equivalent in case of future problems.
the one thing i don't have is a test kit for hardness.i always thought hardness and ph went hand in hand.if ph is good then hardness is good.i also get calcium build up on the top of my tank...very hard to scrap off.so i assumed it was good.(assumed...is that a bad word?)
anyway thanks LHG