Help: Internal bacterial or parasitic infection?

[noncentric]

So, I think some of my zebra danios have an internal infection.

I had 6, then one got really listless and skinny and I moved it to my 6-gal (which had 2 ghost shrimp at the time, no minnows) - the other 5 danios seemed fine. That fish disappeared overnight a few days after being moved. I figured that the ghost shrimp must've eaten him, since there was no sign of his body anywhere inside or outside the tank.

I got the minnows, and moved the 2 ghost shrimp to the 25-gal so the minnows would have the 6-gal to themselves. One ghost shrimp got lethargic and died, while the other seemed fine. A few days later (yesterday), that second ghost shrimp also got lethargic and died and I noticed that 1 of my 5 zebra danios was behaving/appearing like the 1 that had died a while back. And today a 2nd zebra danio looks in poor condition too.

I suspect there is some internal bacteria or parasite in the 25-gal - probably originating from the ghost shrimp. The 2nd (and final) ghost shrimp that died yesterday had something protruding from it's anterior underside (near its mouth). Looked like it might be a worm of some kind, but I'm not sure.
EDIT: found a picture that looks like what was protruding from my shrimp
http://www.fishpalace.org/bacterial_laura.jpg

The 2 sick zebra danios don't have any external signs, just skinny, lethargic (they hang out by themselves), inappetant (they swim around the food, but don't eat), and one's dorsal fin is always upright. No redness, no external growths, no white spots, and no abnormal breathing.

Water params (AP FW Master test kit): temp 79 F, ammonia=0, nitrite=0, nitrates=5-10, live plants, no CO2.

I'm trying to decide what to treat with - I want to treat the entire tank, so something safe for live plants and otos:

Is Maracyn-II a good choice? Looks like it's a 5-day treatment (with a double-dose the first day).
Is there something else I should use instead of, or in conjunction with Maracyn-II?

Thanks!

 

[Lotus]

Maracyn II is a good choice for bacterial infections. It won't really help with internal parasites, though. You can treat with Maracyn I at the same time, to cover more bases with bacterial strains, but it can disrupt your biological filter.

 

[noncentric]

Thanks Lotus! It sounds like I can treat with both I and II at the same time, which sounds good. I may try that.

Not sure from your post, but does only Maracyn One disrupt the bio-filter? Does Maracyn Two disrupt the bio-filter too? Is it a gram-neg vs gram-pos issue?

Thanks!

 

[Lotus]

Yes, you can use Maracyn I and II together, and they do work well together. Maracyn I is more likely to disrupt the biological filter, and yes, it's a gram positive/negative thing. If it does happen, it's usually a short ammonia spike (a couple of days) if your tank is well established. I've used Maracyn I and not had a problem, but it is common to have a small parameter spike.

 

[noncentric]

Well, after doing some more research and more observation of the sick fish - I came to the conclusion that it's an internal parasitic infection (rather than bacterial). I had added some aquarium salt to the 25-gal in the hopes of making the sick fish a bit more comfortable. Soon after, I noticed white stringy poo (with cotton-like tuft at the end) from the two sick fish. This made me lean towards parasites.

All the fish in the 25-gal were more active and seemed more comfortable after adding the salt, even the two sick danios. They were more active and didn't isolate themselves as much, but still didn't eat. I got both Jungle Parasite Clear and Maracyn Two. I figure I'll use the Parasite Clear (probably two treatments 48 hrs apart) and then observe for a few days before deciding whether or not to use the Maracyn Two. I'd really prefer not to use antibiotics if not completely necessary.

In the meantime, between when the fish fell ill and I got the medications, one of the zebra danios died. I examined (cut it with a blade) it after it died and noticed some thin, white wormlike things inside it's chest/abdomen. That does sound like parasites, right?

I then had the Jungle Parasite Clear and dosed the 25g tank with 2.5 tablets (1 tablet per 10 gallons). I dissolved the tablets in some tank water first, then poured that into the tank - since that's what the instructions said to do with soft water. I'm planning to retreat in 48 hours after doing a 25% water change, but am thinking of corralling the sick fish into a smaller area (using a large 5" net) and pour the dissolved tablets over them so they get a more concentrated dose.

I now have 4 zebra danios left, and only 1 (the sole long-finned one) remains healthy and eating.

We'll see how it goes. Many of my anacharis stems are disintegrating due to the salt I added to the tank last week, but the other plants seem to be okay. The java ferns turned white for a few days, but have bounced back.