Identifying small, brown circle...

[refalo]

I had a new addition 3 week ago, this being a juvenile (8cm) Naso vlamingii . Tankmates are – A. percula, C.bispinosa, P. semicirculatus, Z. scopaz and A. straitus.
I never seen what one can classify as an aggression with scalpels – but every day, usually in the evening A.straitus patrols the whole tank, I observe him while getting close to the vlamingii but never touch him and not only to this one. Moving on.
This fish has a very big appetite, and I feed them twice/once a day when giving them TetraMarin Granules (New BioActive Formula), and once a day when giving them frozen spinach, Artemia, Spirulina, Dried Chlorellea.
Water Parameters– NO2 – 0.2mg/l, NO3 – less then 12.5mg/l, pH – 8.5, Specific gravity – 1.018. (Tetra Testkit)
The reason for the thread – (here follows the noticing I observed)

19th October 07 - 3 grayish circles on the lower abdomen + 2 white patches (pale) on the first 2 dorsal fins and on the last 2 as well. Said this there are no signs of weakness overall, always wants to eat.
Has a 150 GB/min but he has been always very active.
21st October 07 - again no sign of stress, test indicated that there is no nitrite poisoning. Circles still present and even white patches
23rd October 07 - the white patch at the lower end of the dorsal fin disappeared – 2 faint circles (cloudy in appearance) appeared by the right side if you look at angle. Lower abdomen circle seems better - in the beginning there were 3 now there is only one, but is a bit brown (not solid) – its like 4mm in diameter

The fish as I said is not showing any signs of flashing. He is always interested in me when I come near by, and never hide. He’s always swimming around.
I did not quarantine the fish since I don’t have an extra tank for quarantine. I acclimatised the fish by placing the bag floating on water for 30min, and then gradually I added small amount of water very slowly till the bag filled up all (took me about an hour).
My tank holds 100gallons. And the salt I use is AquaMedic. No medication were used.

As one can realise from the above my question is concerned about the brown circle, can any one help me identifying what is it?

Thank you in advance

refalo

 

[roka64]

WELCOME TO AA!!!

Is there any chance of getting a pic? NitrItes are toxic to your critters, I would suggest a few PWCs to get them to 0. Did you test for ammonia?
Looks like you love tangs. That Vlamingii Tang will need a larger tank than 100 gallons.

 

[ccCapt]

Just by reading what you posted here, I suspect a water quality issue. If your test shows nitrites, you should check for ammonia. 3 tangs, a coral beauty and a Koran angel in a 100 g tank? Thats seems like a heavy load. SG 1.018 is way too low also. Bump that up to 1.024-1.026.
I would do a bunch of water changes and see if there is any improvement. Sounds like it may just be a bacterial or fungus problem due to water quality.

 

[refalo]

thankyou, yes i love tang - as you said he for sure will need a bigger tank in the future - with the posibility of reaching a lenght of 70cm. PWC is planed for next week - chance for the water to mature. dont have an ammonia test kit at the moment. so you think it the level of nitrite which might has coused this?..also since i tought that this was the source of the problem - last Saturday i added 25ml of Ammonia Detox (Kent) as instructed by the bottle

refalo

 

[melosu58]

I also suspect water quality issues. Nitrites are lethal to Sw fish and you need to do some frequent PWC`s now. This should be your first line of action.

 

[refalo]

yes i have to bring nitrites back to 0.

 

[roka64]

You really only need to pre-mix your water for at least 24 hours before doing the PWC. I would also suggest getting an ammonia test. I also wouldn't use that detox stuff or dose my tank with anything I don't have a test kit for. Cccapt also brought up a good point, that I forgot to comment on, bring that salinity up a little with a few PWCs, maybe twice a week (to also help with the nitrItes) to the previously stated salinity of 1.024-1.026.

 

[refalo]

yes i now about the mixing - infact plans changed and im going to buy the salt tomorrow and WC do it on saturday, i said next week in one of my replys since to buy the salt i ve got a long way. but i figured it out for tomorrow. Ammonia Detox does not only reduces ammonia from the tank but also nitrites and nitrates - for which test kit i do have. in fact i bought for the simple reason to reduce nitrites from the tank.
at the shop no ammonia test kit is available since he told that he has to buy them in large batches and its not worth it. tomorrow ill see if this shop from were i buy the salt has at the moment.
about the salinity, it was the next thing to do, but last time didnt have enough salt to rise it up.

 

[cmor1701d]

You really need to keep enough salt on hand to do frequent partial (10% - 20%) water changes. As everyone else has mentioned it appears you are having a slight problem with water quaility right now.

How long has your tank been running?
What is your filtration system consist of?

Are you able to complete daily 5% or 10% water changes? Frequent small water changes are usually better than infrequent large changes.

 

[Hara]

Are you able to complete daily 5% or 10% water changes? Frequent small water changes are usually better than infrequent large changes.

That would be true unless you are trying to remove something that can be deadly to fish such as ammonia or nitrite... then you need to do a large water change of 50% followed by daily smaller water changes until the threat is gone.

 

[refalo]

Atman EF-3 External Canister filter and a top Trickle filter all along the lenght of the aquarium (which is 5ft) - both are filled with bioballs, Ceramic rings, plastic mats, and synthetic fibers floss . the system has been running for 3 years.

i have a JEBO venturi Protein Skimmer - and regarding this i ve got a little problem, last saturday i had to do some maintinance and had to remove the protein skimmer, when i placed back the skimmer foam formed was very little. i removed it again, checked the whole from were is sucked and it was clear, checked the water pump and the force by which water is being driven up and it was normal, positioned the skimmer back exactly as was, but still bubbles produces are not creating stables foam like they used to and thus none is collected in the resservoir. i even installed an air pump but it was usefull....any ideas what might be going wrong?

edit: as i read from other post its better to rise the specific gravity slowly over a week....so i think its better to do minor PWC every day and elevate it to 1.024...