Well, I reread my post and I can see where it could be assumed it was my tank that was green. Nope!!
But I know the tank in question and the owner well.
I could name fish that do salt and fresh, clear and muddy if necessary due to weather, clear only and muddy only or art least have the preference. But I ain’t going to. So there. Some ignorance a person just has to live with or fix themselves. I am old nuff that what I know is only found in museums of old wrong beliefs.
Lot of good info in the thread, advice and a couple new parts I did not officially know other than common sense, of which I have only a little.
Our little tank, 10 Gal. I think, 2 goldfish (carp), 3 small catfish and 2 baby bass looking fish which are the biggest.
I have heard that most fish will not out grow the tank (space) if fed correctly. ( Not too much as said up thread about over feeding.)
Filters = $$$$$ so I make my own and change after 2 to 4 days.
Scrub walls and stuff at 5 to 8 day intervals and then everything in the tank comes out every 30-40 days. all cleaned including bubble bar and submerged filter pump.
Water is added as needed all along and on the big clean, ¼ to ½ of the water will be changed.
Seems to work good. Water comes from the refrigerator filter to a Brita® pitcher to people & animals & fish. (Yeah, I am fussy about water in my delicate condition of ‘old age.’)
So far so good for about 10 years.
Wife bought a Betta which lasted about 10 hours after we got home with it. Put it in a smaller tank right next to the gold fish tank and it died. WOW!! No idea what got it, I suspect there was something about the water or a few seashells and stuff she added. That stuff had been washed, was old and had been soaking for months, then rinsed before going in the thank. But he/she/it died and wife was not happy camper but I had nothing to do with it so I was innocent thank goodness.
I still wonder what level a fish knows or is aware of things with no more brain than it has. They do have enough brain power to be a fish, that much I think is correct.