Zebra Danios dangerously skinny

Question
QUESTION: I currently keep 4 zebra danios, 1 lyretail guppy, and 1 male marigold swordtail. The remainders of 22 fish after cottonmouth and other diseases ravaged the tank. For the past three weeks I've noticed one of my zebra danios getting dangerously thin, He has slowed down and doesn't dart around all the time like the other danios but he still swims fast and eats well, just seems to get tired easy. I don't think its fish tb because no bent spine or other symptoms and I think he would've passed by now. I also noticed it has spread to another danio now. I would like to know what is afflicting them and what I should do about it. I also have shrimp on order that should arrive any day now. I have a hospital tank (10 gallons). I have a 30 gallon tank with a 10% water change daily (Yes, I know it's not necessary but I don't want nitrate to build up.) Thank you for your time.

ANSWER: Hi Trent,
I'm actually glad to hear you do daily 10% water changes on your 30. Daily water changes are wonderful for good longterm fish health.

There are a few reasons why your Zebra Danios may be getting thin. My first thought is internal parasites. Internal parasites can plague a fish for quite some time. With the infected fish showing signs like progessively getting thin despite eating well, becoming sluggish, showing pale coloration and thin white/clear stringy poo. Treatment -usually- is easy and recovery rate is quite high. I've used Prazipro, which can be fed to the fish directly as well as added to the water. Within a couple of weeks the fish should be better.

Some people also use garlic extract in the fish food to help deter internal parasites in the fish's digestive system. There are also certain fish foods that contain a high level of garlic already.

Old age is another possibility. Fish can age quite quickly. But I'd be willing to make sure that internal parasites is not to blame first and foremost.

I hope this helps and good luck!
Susan~

---------- FOLLOW-UP ----------

QUESTION: Thanks for your suggestion. Sadly, one passed away today before I could get any medication. I was wondering though, I have introduced my red rili shrimp (They are so awesome!) and I am concerned that this medication will harm or kill them. Does Prazipro have copper in it? and will these parasites infect my shrimp? Thanks.
Trent

Answer
I'm sorry to hear that!

I don't believe the parasites will infect the shrimp. And from knowing the experience of other fishkeepers, generally prazipro is safe for shrimp.

Here's a link with great info about Prazipro medication -
http://uskoi.com/prazipro.htm

I've honestly never heard of Red Rili shrimp until now! They are awesome!

I hope this helps!
Susan~