Clownfish sick with internal parasites?

Hi, I bought 2 clownfish about a month ago and one of them died of what I suspect is internal parasites or bacteria--there are no external signs of sickness but fish breathes heavily and gradually starts to eat less. Takes about 3 days for things to set in completely. So I have one clown (true perc) left and I bought him another mate 2 days ago, they got along great and did their dance and stuck together. But now the mate is doing the same thing that the first clown did--breathing heavily and not eating much but looks great on outside and swims ok.

I've heard that parasites/bacteria are always present in aquarium systems but i'm wondering if i might need to dose my whole tank once just to reduce levels. My water quality is good (ammonia=0, nitrite=0, nitrate~20, pH~8.2, temp~75, buff~300) but this tank has been set up for a while (several years). I had a die off several months back and recently got around to recleaning out the tank, cleaning off the liverock and doing two large water changes in a month for water quality. I then waited several weeks before getting new fish and had a healthy damsel in the tank during this whole process (never got sick).

So yes I'm just lost; is my tank damned? Do i need to dose the whole 70 gallons (60 tank + 15 sump)? I am trying to get a sick tank now for the clown that is starting to act funny--I know I should do this but wondering if my water is looking good and has for 2 months if I could still be harboring a bad internal parasite colony?

Any advice appreciated. thanks

tank specs:
60 Gallon TruVu with 20 Gallon Sump
(ammonia=0, nitrite=0, nitrate~20, pH~8.2, temp~75, buff~300)
about 40 lbs liverock

 

What do you have for flow in the tank? Do you have good surface agitation or an airstone? Do you have any type of mechanical filter or skimmer? You are very light on rock.
The other thing I would think of is ask your LFS if these are captive bred or wild caught clowns.

 

i have a Koralia 4 in the opposite corner on the bottom from the overflow. that thing MOVES water; i had to put liverock in front of it to slow the flow a bit but i have good water flow in the tank.

I do have a protein skimmer but it's not been removing much of anything. it makes the small bubbles and there's foam but nothing much in the foam. i just cleaned this tank out twice replacing 50 gallons of the 70 in the span of a month. water quality checks out fine (see specs above).

i do want to get more liverock but wouldn't this just help water quality? which seems to be fine now due to sump and my frequent and large changes as of recent. I mean, I plan on getting more liverock but what would this do about parasites if i'm maintaining good water quality irregardless of liverock?

basically what i'm asking is this--I have good water quality (at least with all the tests i've performed). is it possible to have a parasite issue even with stable water conditions? is it common for people to dose their whole tank even with good water conditions? this would be really expensive for me to do. i'm working on getting a sick tank, but am i overlooking something on my big tank?

thanks

 

some parasites have been known to take up to 3 months to completely go through their life cycle. its like 1 in a million but it happens. i should know. not only am i the president of the parasite club i am also a member

 

she lived!

mastamind thanks for the funny comment just wanted to update and close this thread with info--my new clownfish lived! not only that but seems to be thriving. the LFS told me that it was common for new fish to not eat much when introduced to new foods. I asked "what did you feed it in the store?". they told me "mysis shrimp". i gave that thing mysis shrimp and it ate like a horse. then finally started taking all other foods (flakes/brine/cyclops). So, I dunno I was paranoid after losing a clownfish before with similar issues but this one lived. Hopefully they will pair up someday.