Yet there is nothing wrong with him keeping 7 fish that will all grow over 10" inches in a 210? Have you gone diving recently and done some research on what size territory these fish actually occupy? Or even read some reports on it?
To make the statement that I think keeping clown fish in anything smaller than a 90 gallon tank is silly. Different clown fish come in a variety of sizes and yes I do think its wrong to keep clown fish that grow larger than 3.5" in a tank smaller than a 90 if they are very active fish. Black/white sebae clowns and my allardi clowns are much more active swimmers than my false perculas that sit in an anemone all day, so yes they have different habitat requirements and shouldn't be kept in the same size tanks when they are full grown.
But of course you are not comparing apples to apples. Keeping a 14" fish in a 210 alone is more than pushing it, but to keep it with 6 other very large fish is not responsible or considerate.
I've read a lot of different articles by "experts" this evening on keeping large fish and even a lot them don't stress the importance of leaving very large fish in the ocean or having a public aquarium sized tank. Several of these articles failed to mention the fact that if large fish are kept in tanks that are too small for their needs, that they can have stunted growth and often die prematurely. I'm not making this up, I am quoting other people like Bob Fenner that have articles on the subject.
Most articles on puffers fail to mention that puffers like a very diverse aquarium habitat; that they are very intelligent fish, and that its important to have lots of hiding spaces, complex rock work, plants, and a sand bed for them to dig around in and explore. Otherwise they tend to get bored over time and develop bad habits.
So after doing all this research I have come to the conclusion that its not hobbyists' fault that they aren't more thoughtful with stocking their reefs, a lot of the blame should rest on the shoulders of so-called experts that write these articles about keeping big fish. One guy wrote an article about his puffer Floyd that he had had for five years and had grown to a size of 10 inches in his 125 tank. He was in the process of moving it into a 225 tank. Neither of these tanks are an acceptable size for a 10" fish.
A different article talked about Queen triggerfish, they can grow up to at least 2-2.5 feet in the wild. The writer said that on a reef these fish have a territory of at least a few hundred square feet. So how can you tell me that a fish that is going to reach an equivilent size is going to be happy in a 210 size tank?
Its different when we keep corals that out grow our systems, they end up stinging stuff and we go "oh crap, I guess this coral is too big for my tank". But if fish look healthy to us, we often don't care if the tank they're in is too small. Just like I have seen plenty of people in my lifetime that keep Macaws (type of large parrot) in 4 foot cages or less. Those birds roam entire rain forests.
I don't think there is anything wrong with promoting the idea that we should only keep fish that will be comfortable in our tanks. This means that you may have some fish that are pushing it a little, but still have plenty of room to swim and be happy. This is not the same as keeping a whale in a bath tub, where the only thing the fish can do all day is swim from one very short end to the other. To condone this point of view is wrong and if that makes me the fish police, so be it.
In many ways this hobby is still young and there are many concepts that need to be challenged and changed. Too many people still view the reef creatures they keep as "living art" or learning through trial and error instead of researching before you purchase a coral/fish. A much better form of stocking your tank is to purchase fish that will grow into your system, not fish that you know are going to out grow their tank within a year, but you really want one so you get it anyway. Those reefers have to worry about upgrading to a larger tank just to accommodate too large fish. It takes most people a long time to be able to afford a tank upgrade and in the meantime their fish aren't getting any smaller. Large fish aren't like keeping reptiles, they won't grow to only a certain size depending on the size of their tank. Anybody thats ever kept a grouper can tell you that.
So why not compromise when stocking your tank and say "I'd really like to keep that fish but 10" is just too big for my 75 and so let me see what other fish are in the same family that might be smaller and will do better in my size tank." There are some really cool dwarf puffer fish that can easily be kept in smaller tanks.
Just like when I got my radiata, I researched the different lions out there and realized that a volitan would grow too large for any system I had or would upgrade to in the near future. Even radiata's are supposed to reach at least 8" at adult size and I worry whether I will be able to provide him with an adequate sized tank. Over the past 3 years he has grown slowly and I don't over feed him, so we'll see. When the time comes that he out grows his 3x3' tank hopefully I will have a larger tank or I will find someone that has a better system for him to live in.
Keeping reef creatures should be viewed as a privilege, if we are going to remove these animals from their natural habitats and expect them to be happy living in a small glass box for the rest of their lives, then the least we can do show them some respect/care and try to give them the best environment possible. I'm sorry for being a conscientious reefer, I guess someone has to be.