Hi Jesnon,
Thanks for the photograph. I also realised that one of those “balls” was on the photograph of Ace you posted before...
From what I can see, these balls are small (2-3mm?) and slightly fluffy – am I correct?
Now, I have an idea of what it could be – but I may be wrong!
This is definitely a type of fungus. I do not think it is a dangerous Saprolegnia, however.
See this:
http://www.flickriver.com/photos/tags/saprolegnia/interesting/Saprolegnia is dangerous to fish but none of your Endlers have any growth on them – so, luckily, - I think this is not the one...
Then there is one of the water moulds – Oomycete...
See this:
http://www.google.co.uk/imgres?imgurl=http://upload.wikimedia.org/wikipedia/commons/2/22/Water_mold_Mizukabi_colony.jpg&imgrefurl=http://en.wikipedia.org/wiki/Oomycete&h=720&w=689&sz=50&tbnid=wqe9jM2z87dALM:&tbnh=88&tbnw=84&zoom=1&usg=__G4_w3htdSO8u8Y5lugI3Q90UFMU=&docid=TnwQG7QQZ9SMoM&sa=X&ei=lQFXUtHoLeaS7Aa0ioDgAg&sqi=2&ved=0CI8BEP4dMAs This one is what I think your “balls” are... or at least something very similar or of the same genus.
The good thing is that it should not be Saprolegnia all things considered.
The thing to address is the fact that you may, indeed, have some problems in your tank. I think these are caused by an imbalance and disturbance after moving the tank. This is not your fault – you did everything correctly. It is just some people are luckier than the others if even all of them did everything in a correct way...
So, as I think this is not a dangerous fungus but still the one which shows some general problems in your tank, I would suggest a few things. First of all – please, do not rush to medicate. Medication when the problem is only a “best guess” can do more harm than good (on a side note, I very rarely use meds and I have even cleared a white spot without using any meds/salts/elevated water temperatures). Everything is in good hygiene and as little stress to the fish as possible – this is what I swear by, anyway...
I would suggest hovering the gravel on a regular basis (a little at a time but often) with little and often water changes (you did also notice an unusual amount of “muck” – perfect feeding grounds for fungus and such!). I would do these small water changes as often as possible – 3 litres at a time daily or when you can, perhaps? If you can, pick up those “balls” as well – by hand or tweezers... Also, buy some Hornwort plant (sold on Ebay), wash it properly, rinse in dechlorinated water and pop it in. It may not be the look you would like for your tank aesthetically but coping with it for some time will help. Hornwort is not expensive but it should help by “sucking up” any “nasties” (organic or inorganic) in your tank. You can remove and dispose of it later on when everything settles...
This is what I would do. I would ONLY move to any more “drastic” measures if the problem persists...
P.S. Your resent losses in the tank may have been aggravated by the imbalance but I do not think that this imbalance actually killed your little fellas...
P.P.S. This is a suggestion only – I cannot claim I am 100% sure but this is what I would do if it was my tank...