Is it really sick?! -large angel

[Missmuffet]

Hi this is my first thread so apologies if I have done it incorrectly!
I have a large angel in my tank that appears to be absolutely fine but is not eating I haven't witnessed it eating in a week or so now! I haven't seen it going to the toilet either but bear in mind I can't watch it 24/7 (as much as I'd like to!)
My tank is 180ltrs Community tank
Internal juwel filter I use wool Pre filter pad, nitrate sponge, 1 coarse sponge and 2 fine sponges don't use carbon sponge because I add some plant food and occasionally some anti hair algae treatment as if I don't this does appear as my tank is near a window and gets alot of light
Readings are all 0
Do a 20% water change every week along with a good vac as I have sand substrate and 8 or so live plants (= messy bottom!)

It seems to be looking a bit thin now compared to the other I have but has no visible signs of illness, it's swimming around fine, not gasping, still quite brightly coloured (black white and orange marbled) and no one else is picking on it as far as I can tell which in my experience they do when I get a poorly fish.

Everyone is fed on a mixture of flake and frozen, it seems interested in food but doesn't actually attempt to eat it and then just swims off, no one else is ill and haven't lost any fish in a long time

Other fish in my tank are 3 other angels another of which is large and 2 small/medium ones cardinal tetras, small plec, pair of gbr's, 3 Bala shark, 4 panda corys and 1 clown loach ( I'm well aware he should have friends but on adding him +2friends (with the intention of upgrading my tank this year) about 8months ago he was only survivor and I haven't quite decided how I want to follow this up!)
Oh my I nearly forgot Sebastian!!!!! My red clawed crab!!! I only added him thurs as I rehomed/rescued him he will not stay if he causes any problems tho!

On the whole if my fish are sick I know about it because I know they are just not right or their normal selves like this guy and usually there is something visible I can go on to diagnose but in this case I have no idea I'm thinking maybe something internal/bacterial? But I guess I'm just hoping someone will say 'ahh don't worry my angel occasionally does this when he's had a barney with the misses' or something! Iv only had Angels for around 8 months so I'm not exactly the most experienced when it comes to their particular habits
Also I have no way of quarantining any of my guys

 

[librarygirl]

So this tank has been running for 8 months right? What kind of filter is on the tank?

I'm afraid you're massively overstocked and a 20% water change weekly isn't enough. Also you're going to need a much larger tank for the shark and clowns. Also the sharks may end up seeing the GBRs, tetras and corys as food.

The angel could be stressed due to overcrowding. The sharks may be harrassing them too (a lot of that tends to happen when lights go out so you won't see it).

I'd start with a 50% water change twice per week with dechlorinator.

What test kit are you using? With that many fish you should have some nitrates; if you're using strips they aren't accurate. The API Master kit is recommended.

You should find a way to quarantine the fish to observe him and see if he starts eating on his own. He might just be stressed. You'll either need to upgrade the tank ASAP to at least 200 gallons or start returning some fish (the sharks and clown would be a good start; you'd still be overstocked even without them but it would be a lot better than what it is now and the fish may be more relaxed).

 

[Missmuffet]

Hiya tank been running for 9 months approx just taken a pic of nitrates, nearly a week since last water change I would say they are between 0 and 5ppm but change is due in next few days i always use api master kit
Iv never done more than 20-25% changes weekly in any of my tanks unless there has been a problem I had white spot in this particular tank a few months after setup after I added some tetras, (which really annoyed me as I spent probably the best part of 30mins staring into the tank at the lfs to check they all had no signs of it!)
That's possibly the only time I have done a 50% change and even then it wasn't because my water quality was bad it more to do with me vacuuming the bottom like mad! I always take my water to lfs when I know I'm going just so they can test it with their kit too and they have always said its perfect

Had to look up filter specs (eek) just always taken for granted it was filter designed for tank its the juwel compact H 600lph its an internal one

As for being over stocked yes you re right but it's always been my intention to upgrade my tank and as most of my fish apart from the two Angels are still small I'm not overly convinced on getting rid of any just yet bigger shark is approx 2 inches and my smallest shark has more chance of being eaten by the biggest cardinal lol than the other way round!

I just can't separate him at the mo I have no spare tanks I have containers that would be suitable but no spare heaters or filters and unfortunately I'm not in the position to go out and buy spares at the moment and being in England he would most definitely need at least a heater!

I can see he is stressing about something just don't know what I'm not convinced he is getting picked on either he has not a mark on him, so I guess being off their food isn't normal for Angels then im now gonna stop typing angels as my **** phone keeps turning it into Angela and I'm fed up of changing it lol!!