fish all dying please help!!!

[featherfin]

i think one my tanks has contracted an agressive form of fin rot. i woke up this morning and two of my fish were finless and dead. another one has most of its fins missing. the rest look fine. i hadn'y noticed anything yesterday so it was a big shock to find seemingly healthy fish dead. i have never had anything like this happen to any of my tanks before so i don't know what to do. i am setting up a quarantine tank and i'm thinking of moving the fish that i know are sick into it. is there any sort of medication i can use to treat them so i don't lose more?

any help is great.

thanks

[featherfin]

the fish that got hit were a betta and a sword, apparently they are most likely to contract fin rot. i do weekly water changes and i did one yesterday with a full scrub down and filter rinse. i know that it is not poor water conditions that are causing it. i also noticed that my betta had a bit of white around his fins but i thought it was just his natural color because he's had it since i got him. i also changed the filter box ( kept the same media) could that be it?

[beowulf]

Can you list everyone that lived in the tank?  It could be an aggressive tankmate.

[PaleoFishGirl]

What are your water parameters? Is there any limestone in your tank  (rocks, fossils, etc.)?

[featherfin]

the only aggressive fish are a rainbow shark and a pictus catfish. neither have been aggressive towards any of the fish. the bettas are young and the kribensis are very passive towards the other fish. the swords, platties and corydoras are not aggressive. i did move my young featherfin to another tank yesterday becuase he had a small cut i just noticed and i was going to treat it and put him back in. i didn't want to put the sick fish into the tank with him so a am setting up another tank.

[beowulf]

Rainbows can get nasty pretty fast.  I have seen mine chasing around my SAEs and if the kribs pair off they can also become very aggressive.

[PaleoFishGirl]

You never know what happens when the lights go out, either...

[babblefish1960]

i do weekly water changes and i did one yesterday with a full scrub down and filter rinse. i know that it is not poor water conditions that are causing it.

I am very curious to understand what it is that you mean when you say you performed a full scrub down and filter rinse.

What are you scrubbing down, and what are you scrubbing down with?
This may be a very important detail for which may help unravel this mystery.

Moreover, what do you rinse when you do a filter rinse, and what do you rinse it with?
You see where I am going here, I am a proponent of good grunge remaining in order to keep the beneficial bacterias and infusoria intact.

Additionally, when you change the water, where is it coming from, and what are you treating with, and how much are you treating?

I am also a fan of Seachem Prime, and whenever adding tap water or untreated water to a tank, the volume of the entire tank must be treated, not merely the volume you replaced.

I am currently very suspicious of what is coming out of the city water taps these days, I feel they are over compensating for something else that may be worse, such as a very advanced nutrient bloom.

On another note, when you removed the various fish, and scrubbed down the tank, did you remove plants or decorations or anything that may have left the remaining fish more exposed thus being susceptible to more stress, which can present itself in the symptoms you have described here.

[Jeff1192]

From my past experience with fin rot it doesn't usually progress that fast. I would think it is more likely an aggressive tank mate. Rainbows can be aggressive, especially after lights out when they tend to me more active.

Jeff

[featherfin]

by full scrub down i mean taking one of those magnetic glass cleaners and cleaning the glass and syphoning the gravel. by filter rinse i mean rinsing out the filter sponge in a bit of water syphoned from the tank. i lost the featherfin but everyone else seems fine. does anyone know what might cause a rainbow to suddenly turn aggressive?

beowulf: the kribensis did just pair off into a coconut.

[beowulf]

by full scrub down i mean taking one of those magnetic glass cleaners and cleaning the glass and syphoning the gravel. by filter rinse i mean rinsing out the filter sponge in a bit of water syphoned from the tank. i lost the featherfin but everyone else seems fine. does anyone know what might cause a rainbow to suddenly turn aggressive?

beowulf: the kribensis did just pair off into a coconut.

It is just normal behavior for them, at least from what I have seen.  Also a pairing of kribs can be very aggressive as I lost two male kribs to my paired couple.

[dan2x38]

Babblefish mentioned Prime water conditioner... what do you treat your water with?

[featherfin]

i use aqua plus tap water conditioner and i use the dose for a full tank, not just for the water i have replaced ( 2 capfuls). i have identified the culprit , it was my rainbow shark. it has been systimatically hunting down and killing one fish at a time! it was after the pictus cat when i caught it. i moved it and the tank seems much happier now.

[PaleoFishGirl]

Yay, I'm glad you sorted this out!

*featherfin's remaining fishies breathe a collective sigh of relief*