'nother newbie Uisce has been in a new 5Gal tank 5 weeks and started showing deterioration of his caudal and anal fins. He also abandoned his bubble nest at this time and developed white-looking translucent patches on his blue fins. Fins don't have dark edges, but caudal fin appears to not fan out as well on top or something. There is no apparent velvet, ich, speckling or spotting, though before the fin issue his color appeared faded or masked, briefly. He's an aggressive boy and this too suffered, briefly, but he will now engage and attack a finger. There's no apparent cycling issues. I remove and replace 1 Liter per week, nitrates/nitrites/ammonia are all zero (using API five-in-1 and a seachem ammonia alert that's 8 months old. Ph is 7 hardness is GH 30 or less, KH 40 Tank is bare bottomed, with bridge and boat furniture, a heater - 78-80 degrees, and I use an improvised siphon vac to remove feces and precipitates with the 1L refresh, though this week i've done an extra 3.5 L replacement. No filtration. I suspect there might be contamination from the gravity filter I use for dechlorinating tap (activated charcoal) as this became the primary water source about 4 weeks ago. There is also dark flecks precipitating out on the floor now, in addition to his poop. it gets peppered over the course of a week.