It is definitely about water quality. Stocking guides are just that GUIDES. Water change schedules can completely undo the best and larget setups and can compensate (to a point) for overcrowding (but this should not be an issue).
reptileguy2727;4447002; said:Why wouldn't you put platies with goldfish?
QUOTE]
Because of the temperature difference. I prefer to keep goldfish at around 75F, I keep all tropical fish in the 80's. Coldwater+Tropical is just not a good match imo.
The same way you would for any other fish, by thinking about their maximum size, amount of waste production, activity level, etc. And it is not the same thing as what you said. Going by your rule, it's a minimum of 10 gallons for one fantail and 20 gallons for 2, but imo, one fantail needs at least 35-55 gallons (depending on the breed) and for each additional goldfish, I would add maybe 5-10 gallons onto that (again, depends on the breed).reptileguy2727;4447002; said:How would you determine how many gallons x many fish need? It sounds like the same thing, just rewording it.
^^Oh, and I forgot to mention, for "single tails", I wouldn't go any less than 75 gallons for a single fish, and 90 gallons for 2-3.