Hey BlackAngel! Welcome to the forum! Sorry to hear about your angelfish though
Before getting on my soapbox, please understand that I am not a fish illness/disease 'expert' or 'specialist', nor am I formally trained to diagnose ailments in fish, or anything else for that matter. IMHO, this is important to know since my following comments are truly only a guess based upon your explanation, and so, I could be slightly wrong, or completely off base. Point being, you will be the best judge of how to treat or react to this issue, but hopefully I can help get you pointed in the right direction.
Ok, enough of that...
Based upon what you describe, this sounds like your angelfish could be experiencing one or more issues so perhaps a little more information would help narrow things down a bit:
- Where exactly are the white 'marks' located on your fish? If you were to cut the fish in half from its mouth to the middle of its tail fin, are all of the marks located in that general area? *If so, this is a good indicator that your fish may be suffering from head and lateral line erosion (HLLE)
- What, if any, other symptoms or irregularities that can be found on your fish, or within their behavior (e.g. getting thin, can't swim right/always swims backwards, doesn't eat - basically anything different you have noticed occurring now versus before; assuming you have had them for a while)?
- Do the marks on your angels appear to be somewhat 'hairy', or like a small cotton ball? *If so, this may be a good indicator that your fish have a fungal issue
- If they do not look like a cotton ball, do the marks appear to be a depression in your fish or are they more like a lump which protrudes from the them? *While a depression like marks would be indicative of HLLE, lump-like marks may be a sign of a viral infection
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To be honest, the one thing that is screaming at me right now is your description of the various types of fish you have in your tank...which, in relation to the full potential size of at least one or two of your fish, is a relatively small tank. Going above and beyond the issues related to keeping any fish in a tank which they have outgrown, or could out grow, you may also be struggling to maintain the best possibly water quality - which I am bringing up due to your 'huge pleco' since most do get huge and even as young fish, they create a lot of wastes...hence, possibly contributing to a more rapidly declining water quality. I also bring this up because many, if not all illnesses/diseases/issues can be closely related to water quality since poor conditions would stress our fish...but in at least a few cases, such as HLLE, water quality is very influential. In fact, it is often suggested that the best, if not only treatment for HLLE is to improve both water quality and our fishes' diet(s).
Obviously, I am sure that I have not covered every possibility here, but I think the few illnesses/diseases I have in mind are at least the more commonly experienced issues as far as I have observed. To help out even more, you may benefit greatly from reading the 'how to get faster, more accurate replies' sticky that you can find on the main page of the
Freshwater Aquarium / Fish Tank Forums, or by clicking
HERE - which is were you will find a list of questions which, if you can answer most or all of them to the best of your ability, should contain a higher amount of pertinent information the members of this forum can use to help you better.
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