Well crap

[serenissima]

One of my fish is sick: a cardinal tetra is severely bloated. This is the first time I've had a problem in several months.
For those who are interested in the nitty-gritty details, here are the contents of the lengthy post I made to Age of Aquariums.

One of my cardinal tetras is severely puffed up and has a white fuzzy spot on the side of its tail. It is swimming normally. Any guesses as to what is wrong with it and how to proceed? The earliest I can go to the pet store is tomorrow evening and I'm not sure I'll be able to check this forum before then, but I'd appreciate advice anyway.

I went on a two week vacation last month. I did a water change several days before leaving; it had been three weeks since the last time. Everything looked fine before I left. I had someone drop in a "vacation food" tablet and algae pellets for my otos while I was away. I did another water change a few days after getting home, so that was three weeks again between changes. At that time I noticed how much bigger my cardinals were than when I originally got them a few months ago, especially one particular cardinal.

Since then, I've observed that the one cardinal was noticeably distended -- its stripe has a wave in it instead of being a straight line, and its colors appeared a little faded because the scales weren't lying totally flat to its sides. However, it seemed to behave normally, so I was hoping the issue would resolve favorably on its own. I did another water change one week after the post-vacation water change.

Tonight, though, I've come home to find the fish is so bloated, it looks like it has blisters. It looks kind of like the photos of dropsy I'm looking at right now, but I'm not sure. Also, there's a white bit of fuzz, like a pill on a sweater, attached to the left side of its tail. It still seems to be able to swim fine, and it is not scratching against things.

I feed my tetras flakes, usually twice a day. I skipped feeding this morning because I was running late. Tonight none of the cardinals seemed to have much appetite -- they hung around at the bottom of the tank instead of swarming around the flakes like the glowlights and black neons. Come to think of it, the cardinals have been acting not-hungry for a few days. It's only the one fish that looks sick, though. Unfortunately, it's been a while since I took the time to just sit and watch the tank for several minutes, so I'm not sure exactly when things happened.

Tank size: 20 gallons, 12"x15"x24"
Tank age: about 10 months
Inhabitants: 8 cardinal tetras, 8 glowlight tetras, 4 black neon tetras, 2 Otocinclus catfish, 3 japonica shrimp. No live plants, only plastic.

I do not have a hospital tank available.

Current water chemistry on Wednesday, June 7
temperature 75F
ammonia 0 (I don't usually test ammonia, but did tonight for thoroughness)
nitrAte ~30
nitrIte 0
hardness ~200
alkalinity ~100 (very hard to judge from color strip)
pH 7.3

Recent history
Sunday, June 4
temperature 78F
nitrAte ~35
nitrIte 0
hardness ~250
alkalinity ~80
pH 7.2
Changed ~8 gallons, added 1/4 tsp. NaH2PO4
(I routinely add sodium phosphate as a buffer when I do water changes. My pH was 8 before I started doing that.)
At this time I repositioned the plastic plants, which stirred up a lot of debris.

Saturday, May 27 (post-vacation)
temperature 83F
nitrAte ~40
nitrIte 0
hardness ~400
alkalinity ~50
pH 7.4
Changed ~6 gallons, added 1/4 tsp. NaH2PO4

Sunday, May 7 (pre-vacation)
temperature 77F
nitrAte ~40
nitrIte 0
hardness ~180
alkalinity ~70
pH 7.2
Changed ~10 gallons, added 1/4 tsp. NaH2PO4

Sorry to make such a very long post... I'm not sure what information might be helpful. Thanks in advance for your replies.

Comments

[rhynyx.livejournal.com]

Is there some way to isolate the sick one? If it is dropsy, that's fairly contageous. Plus, it sounds to me like fungus (white cottony threads), which is also contageous, but that one is hidden before you get exterior signs of it. If it is fungus, your best bet is to treat the whole tank, since everybody's probably got it. The good news: I've had fish with fungus who lived to tell the tale. The key is fast action in getting them medicated. I don't remember what I used - I think it was fungus clear, but it came in little fizzy tablets that turned the water greenish blue.

Other than that, if you've got a heater, I'd say turn the temp down a little - diseases tend to grow faster in higher temps - but not too low 'cause fish don't like the cold so much. Of course, depending on the disease, I've heard advice to keep the temp up so the meds have more time to work... Crap, it's been a while since I kept fish and not frogs, so I don't remember clearly.

Looking at the tank history, I'd be slightly concerned about that temp jump and the pH jump looks out of place. If you've got very sensitive fish who are used to a very constant pH, that could be enough to throw them off and make them vulnerable. Remember, the pH scale is logarhythmic (I'm pretty sure I just spelled that wrong, but I just can't find it in me to care enough to look it up), so a .2 difference is more than it initially seems like. Not enough to *hugely* worry, but spoiled little fishies get tempermental over the littlest things, and it sounds like yours are well cared for.

Oh by the way, before you add any medications, do the idiot check and just make sure you've removed charcoal from your filter. No point adding meds if you're just gonna remove 'em at the filter, right? :)

Good luck and hang in there - it's always frustrating to deal with sick tanks. Why can't they just learn to TELL you what's wrong? I want little fishy notes tacked on to the inside of the tank, telling me the exact symptoms and what's going on with 'em.