You Guessed It...Dying Fish

[johncake]

About two weeks ago I added one panda cory and six lemon tetras to my 25 gallon tank (plastic plants, community tank neons, danios, panda corys, running for about 6 months now, 78 degrees, 20% water changes weekly).

For the first three days the new members (panda cory and lemons) were fine, seemingly normal. Over the course of the next week, the cory and four lemons have died. On top of that, one of my neons died too.

I tested the water with the first death and realized my nitrates were probably a little high (likely due to overfeeding I'd guess) in the 60-80 range (who can tell the right color?) At this time my pH was around 7 (maybe a little higher given the color), ammonia 0 and nitrites 0. Temperature at 78 degrees.

I did a few water changes (every other day ~ 20%) to get the nitrates back down below 40, and the other parameters have remained the same. More fish continue to die, first the cory, a lemon, then the neon and remaining lemons (3 more).

I don't have a quarantine tank.

During this time all of the original inhabitants of the tank (save the one neon) are very fine with no visible ailments.

Any thought as to what could be killing off my fish? Any suggestions as to what to do? How to make sure my tank is good to replace my lost fish?

Here were my thoughts as to possibilities:
1. Nitrates too high and stressed the fish to bad health causing them to die. Other fish just used to it so not impacted as much. I've read up on this and I'm not sure that high nitrates could outright kill the fish. Any thoughts?

2. One of the new fish was sick and has contaminated my tank. So now what? Should I proactively medicate? Set up a hospital tank for my remaining fish? Treat in the main tank? Ugggh.

3. The new fish were just unhealthy and couldn't take the stress of a new tank (probably least likely and doesn't explain my neon death).

Your thoughts and time are greatly appreciated. I'm tired of flushing fish.

 

[Allivymar]

Ok. Totally non-professional guesses here

Sorry bout the fish. Can you tell us HOW they died? What symptoms? Anything unusual you noticed? Markings, color, time of death, behavior?

Yeah your nitrates are high. Not horrifically so, but definitely high. I've read fish will acclimate to higher nitrate levels and do fine, but fish being introduced may not deal with it well at all. That MIGHT be the prob with the death of the new guys; doesn't exactly explain the neon.

They may have brought disease in with em. Is why most of us have QT tanks. I am forever buying new fish (LOL its an addiction I swear), but NONE of em enter the main tank for at least 2 weeks. Some people QT for up to 6 weeks to be sure disease doesn't rear its ugly head; I'm just not THAT patient. My guess it is disease as other have continued to die despite the water changes, although you may also wish to contact your local water supply and make sure they haven't added anything/slipped up somewhere.

Its impossible to guess what that disease may be without lots of detail. Could be viral, bacterial, parasitical, water probs. Throw us some more info and we'll see what we can do.

 

[johncake]

Here is everything that I can possibly think of, one by one.

Of the six lemons and the panda, they all appeared on first glance to be in good shape. I didn't see any problem signs in the bag or in the tank at first.

First Lemon - died and found him stuck to the filter. Probably died and was in the tank for a day. Upon pulling out, he didn't look too good being sucked by the filter for a day.

Neon - one of my typical neons, similar size to the rest. No apparent changes, color okay, no lesions, bulges or any other sign of distress.

Second Lemon - After looking at all of my lemons more closely, I noticed one had a place on its side that was reddish. After observing even more closely, I saw that this fish seemed to have something internal that was causing a slight bulge in its side. I subsequently read about diagnosing fish disease and this seemed to be something like dropsy or some other type of infection. This concerned me and I was to remove the fish once I researched the best way to treat. I didn't have to worry about it because he was already dead in the morning.

Third Lemon - Died overnight along with #2. No outward signs of problems, color
was good, etc.

Panda Cory - This guy was the life of the party for about 3 days. Was all over the tank interacting with my other ones. He was a bit larger than the current cory inhabitants so I knew it was him easily. He started laying around the bottom and acting all lethargic. This lasted for 2 days and then he was very weak. No real outward signs of problem. I was going to freezer him because it was clear that he wasn't going to make it. Again, more research and he didn't last long enough. Upon examination, he looked pretty normal too, perhaps some redness along the side toward the back, but that would be me stretching for something.

At this time there was a break in the tank of death. The remaining lemons were acting fine, good color, eating, swimming along with the others. The other fish were business as usual too. This lasted for two days.

Fourth Lemon - again no signs of problems other than being dead.

I've been testing the water daily during my death run and everything seems to be holding rather constant at the parameters previously described. I'll be doing a water change (~20-25%) tonight to help with the nitrates.

 

[Allivymar]

Hrmmm. Dropsy and Septicemia (those red markings) are usually indicative of another disease; they're general not the disease itself, although Septicemia usually is caused by opportunistic bacteria which take over once the fish is weakened and dropsy is a sign of kidney failure.

Its near impossible to guess what the prob is as the symptoms were so vague and unclear. Its times like that you almost wish they had ich; at least you'd know what it is and how to treat.

I'd suggest taking a look here http://www.fish-disease.com/diseases.htm if you haven't already. Great website.

I'd continue with the frequent water changes and I might do a round of Melafix. It won't help with major illness, but is a mild antibacterial and if the rest of the fish are basically healthy may help keep them that way. Fresh water may simply be your best defense.