Update 4 - the last pleco DIED !
Dearest forummers and gurus,
My pleco has died too, approximately 16 hours after my 50% PWC yesterday.
This morning, I observed the pleco closely. It was :-
1) sitting on a leaf at the water surface, I think it was breathing (part of
its nose was above water, I don't understand this, I thought it breathes
with gills).
2) 'bumping' up to the surface for air if it was beneath water surface.
The plece died among the leaves of my water plant, similar to the other 2 goldies I had. Is there something we can read from here : all 3 fishes died among the leaves of my water plant.
If it's true that ammonia was burning the gills of my pleco (which finally killed it), where did this ammonia come from ? I have only one pleco and the single water plant in the tank. Rotten food has been removed yesterday after doing the 50% PWC. This 50% PWC was done without dechlorinator.
Furthermore, the tank looks clean, no cloudiness in the water.
I will provide below my tank system 'ecology' again, after the death of my last and single fish, the pleco :-
1) 1 water plant, probably Java Ferns planted on and tied to a piece of
driftwood (could this be the source of ammonia) ?
2) Many small pebbles, but no sand nor gravel. These pebbles have been
washed many times with water.
3) 1 filter which also acts as the bubble source.
4) Food particles removed, water is clear and not cloudy.
Tank Dimensions : Cylindrical tank, 1 ft in diameter with a water height of approx 10 inches.
I supposed the Nitrogen Cycling Process is still developing in the tank, thus I have not poured away the water. After all, the plant is still inside.
I appreciate your comments, dear forummers.
Furthermore, I am thinking of stocking another 2 small fishes in the tank, to speed up the Nitrogen Cycle. Hopefully, I can go back to seeing nice goldies in my little tank again soon.