Planted Tank Guru
Join Date: Mar 2009
Location: Citrus County,Florida
Five 2" Rainbows is not an insane number of fish but I don't have enough information on whats happened here to do anything but guess.
(and I've thought about it since reading the post)
What is your water source? Is it treated tap, was it aged? Did the large WC done pre-treat go normally?
The stringy material possibly released slim coat off the fish? Stressed fish can produce a ton of slime and any ammonia reading is always a bad thing.
7days plus with low ammonia readings mentioned did it spike at the end after adding the flu and the WC? Parameters can flip fast on small tanks and fungus growth can be explosive covering huge areas overnight so I wouldn't rule that out completely either.
again sorry you lost fish
The Fraternity of Dirt
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2-75g planted, 5-55g planted, 5-20g planted, 110g w/30g sump, 8-10g,
2012 update adding table top pleco pans & a 90g (Nutz)