White Skirt Tetras internal parasites?

[Cup o' Joe]

Tank size: 16 gallon
pH: 8.4
ammonia: unknown
nitrite: 0
nitrate: 20 ppm
kH: 300
gH: 75
tank temp: 80F

Fish Symptoms (include full description including lesion, color, location, fish behavior):
Not very energetic, tend to hide in lower half of tank/inside decorative logs. Eating only half-heartedly compared to the healthy tetras. Periodically expelling white/semi-transparent stringy poop. The texture is relatively uniform (no sign of worm eggs, blood, etc.). Suspicious black segment inside sick fishes' organs, possibly in digestive tract.

Volume and Frequency of water changes:
20-25% change weekly/biweekly. Did 2 of those back to back a week ago due to nitrite spike from medicating. Parameters have stabilized since then.

Chemical Additives or Media in your tank:
root tabs and plant nutrient supplement. dilute (9.5%) sulfuric acid to lower pH. general paraguard treatment 2 weeks ago, then prazipro since then every 4-5 days.

Tank inhabitants:
4 white skirt tetras. Also had a 5th tetra lost to the disease 2 weeks ago.

Recent additions to your tank (living or decoration): none. relatively new tank (1.5 months old)

Exposure to chemicals: nothing I haven't listed

Digital photo: see attached.

Additional notes:
First of all before anyone brings it up, I understand 8.4 is on the high side for pH. My local tap water is very alkaline so it's difficult to avoid. I've been treating regularly with pH buffers but I can't make too much of a change at once. Also, I tested the petstore tank parameters and they have the same issue, so it's probably best that my pH isn't too low so new fish don't get pH shock. Additionally, I've successfully kept black skirt tetras in similar conditions (they lived for 4 years before a tragic moving accident shattered the 30 gallon I had) so I don't believe the pH to be the issue here.

Just to provide a bit more context here. I've only had this tank for a month or two. I started it with some planted aquarium substrate and some standard deco, planted with anubias, amazon swords and java ferns on day two. Around day 5 after the parameters had stabilized I bought three tetras as a pilot group. They seemed to do fine for a few days but then the smallest one began exhibiting these symptoms (minus the black spot) and died before I could obtain any treatment. I waited a little while to see if the others got sick, but they seemed extremely healthy so I chalked up the death to acclimation stress. I then bought two more so they could school. They all did fine for a week before one of the two new ones began exhibiting those symptoms (again the smallest!). At that point I realized it was something else. I immediately started using a paraguard general treatment to try to stall for more time. The second new tetra may have caught it during that time.
After a lot of research my best guess is that it's some sort of internal parasite, most likely some sort of worms. I switched to prazipro dewormer after that. It seems to have stalled the disease from worsening (it's been almost 3 weeks since I first noticed it) but there also haven't been any marked improvements in the fish. The sick ones have gone from just hiding in the bottom to taking half-hearted nibbles at food before spitting it out again, but no improvements since then around 4 days ago. The pooping has stopped but I don't know if that's just because they haven't eaten at all. The larger of the two sick ones has been better off overall and has occasionally chased one of the healthy ones around for a little bit. However like the smallest one it also hasn't eaten at all (as far as I can tell) in at least 5 days. I'm worried that even if the disease doesn't progress they'll eventually starve to death.

TL;DR 2/4 fish are sick (maybe worms). Any feedback on whether my diagnosis is correct/ any suggestions for better treatments, or should I keep on doing what I have been doing? Any help is greatly appreciated!!!

 

[fluttermoth]

It's hard to pinpoint what, exactly, might be wrong, as the fish sin't showing any distinct symptoms of anything recognisable.

Please stop trying to change the pH. Making hard water acidic is almost always doomed to failure; the dissolved minerals just push it back up, and a swinging pH is much more damaging to fish than a stable one.

You need a test kit for ammonia (and liquid or tablet bases tests are better than the paper strip kind, which I'm assuming is what you have. Ammonia is much more toxic in alkaline water than it is in acid, so you need to watch out for any trace of ammonia.

If you didn't fishlessly cycle the tank, and these fish lived through episodes of raised ammonia, then they could have suffered damage that is only now showing up. This is very common in fish that have been used to cycle, I'm afraid.

I would also suggest bullying might be the problem. Widow tetras are very, very nippy fish and need to be in bigger shoals than some other tetras; even six isn't really enough, but your tank isn't big enough to maintain a proper shoal I would consider your tank much too small for this species for that reason.

Your temperature is also far too high for this species.

 

[Cup o' Joe]

The tank was cycled for a week before I got any fish so no problems on that front. Thanks for pointing out the high kH. I hadn't made that connection though it seems obvious in hindsight that the pH can't be adjusted as a result (I know a decent amount of chemistry but never apply it because I'm stupid like that). I don't know what much I can do on the temperature front. I live in the south and my A/C is pretty weak so it's inevitably going to be in the upper 70s/lower 80s during the summer months. I'll try to lower the temperature in that room but I don't know how much it'll help.

Good to know that about widow tetras. I've never encountered that information before. I kept 4 in a 30 gallon tank successfully for nearly 5 years with no issues so I didn't expect any this time around. I will say that I haven't noticed any issues with bullying though. At least in terms of feeding, all of them seem to get adequate chances to get food. I generally do a little bit at a time spaced over five minutes to avoid overfeeding and also make sure all of them get fed.

I'll try to obtain a better test kit, but again I don't think that's the issue. I'm very on top of water changes and making sure food doesn't go uneaten. The only time I've had water imbalances was when the medications screwed up the bacteria populations but I caught that pretty quickly.

I still strongly suspect they're dealing with some sort of internal parasites. The white stringy poop and especially dark spot inside their gut seems super suspicious. I looked at my two healthy ones and they don't have the dark spot in their organs. Plus the fact that they're not eating regularly also points toward that. It's just really problematic because I don't know what specific kind it is so I kind of have to just guess and hope I'm medicating right.

Anyway, thanks for the help all. I'll address what issues I can and just pray for the best with the remaining ones...

 

[Essjay]

If you cycled the tank for a week, you didn't cycle it, I'm afraid. Cycling means adding ammonia and waiting for the bacteria to grow before getting fish. I have done two fishless cycles, both took 7 weeks to complete.

Unless you were doing daily water changes for the fish few weeks it is quite likely that the fish have been exposed to high ammonia and as Fluttermoth pointed out, this would have damaged the fish.

 

[Cup o' Joe]

If you cycled the tank for a week, you didn't cycle it, I'm afraid. Cycling means adding ammonia and waiting for the bacteria to grow before getting fish. I have done two fishless cycles, both took 7 weeks to complete.

Unless you were doing daily water changes for the fish few weeks it is quite likely that the fish have been exposed to high ammonia and as Fluttermoth pointed out, this would have damaged the fish.

Well, the more you know... I was always told that leaving it for a week after adding bacteria supplements and some food is enough. I've seen several sources that say for a small tank adding a lot of plants along with bacterial boosters is enough to get the cycle going in a week. The nitrate readings I had certainly seemed to correlate with that. That's something I'll definitely be more careful next time around though.

Ammonia damage still doesn't seem like the most probably cause however, since the healthy fish I have haven't exhibited any remote signs of ammonia stress. Again, I have to refer back to that growing black spot inside the gut of the sick fish... it just seems too coincidental not to be a symptom. That along with the stringy white poop...

 

[Crystal90]

Here is the link to 'cycling a fresh water tank'. I highly recommend reading this, it really helped me understand the cycling process.

http://www.fishforums.net/threads/cycling-your-new-fresh-water-tank-read-this-first.421488/

 

[Cup o' Joe]

Just an update. The sickest fish died after not eating for a week. The better of the two seems to have made a full recovery however. I'm a bit confused at this point, as the contradictory results really aren't helping me file away diagnostic info for future reference.

I had guessed that it was some type of worm parasite, and the successful treatment of one of the tetras with Prazipro supports that. However, the second one died and I don't know what to make of it. Maybe the disease was just too far progressed by the time I started treatment? I did an autopsy and I didn't find any worms in the deceased fish. The suspicious black spot I referred to earlier (see picture) wasn't a worm as far as I can tell. When it came out it disintegrated into a brown mush, kind of like either a blood clot or fecal matter.

With the new information in mind, I was wondering if any of the experts out there can offer a more accurate diagnosis? I'd like to be able to better respond should a similar issue arise in the future.

 

[SeanTrollope]

how did you do an autopsy on a tetra. it is so small

 

[Cup o' Joe]

Well obviously it's not going to be a super professional operation, but I was able to check for obvious signs of worms. I just made an incision in the ventral region with a sharp toothpick and pried it open from there. No worms in the abdominal cavity. Trust me, I was not happy having to do it but if it helps me protect the other living fish...