Hi,
My point was that at that stage (4-inch?), it seems that the animal does not require an immidiate move to a bigger tank.
While it might be true that tangs will grow to an enormous size, perhaps even in captivity, I do not believe many do so.
In a way, I agree that attempting to assess a fish health status by "looking" at them is not a very responsible and sensible thing. However, what other factors can you use to judge the animal's health?
Just because fish do not show signs of disease or ill-health, doesnt
mean they're healthy.
This statement seems to be contradictory. However, you are on the right track. I assume that you mean to say that the absence of dissease
does not always implies that an animal is "healthy".
The bottom line is that a fish might be "healthy" now, and because of whatever conditions it will become sick later. This happens in overcrowding situations, underfeeding, etc.
Finally two thoughts keep crossing my mind and I whish to share them with you...
I can imagine that this tang vs tank problem could be taken a little bit farther and we could say that fish in general should not be kept in tanks. They are not happy because they do not have the space that they have in the ocean! Damsels keep small territories in the wild, but they have a huge an open space all around them that a tank (even a 200g tank) does not provide!
I also think about my visit to C-Quest, a hatchery in the Caribbean. When I saw what a really well fed, healthy, and well-cared false percula look like I felt ashamed. This fish are huge! (and I do mean huge, at least 3 times as long than my female clownfish and 10 times its mass. Almost Goldfish huge) They are also very old!
Truth be told, the longest I have kept any saltwater fish has been 4 or 5 years. I have kept freshwater fish for a little bit longer, perhaps about 10 years.
So, I stand by my statement. 4 inch tang in 75g tank should not be a problem as long as the rest of the conditions for good SW husbandry are met.