MY temps are always with in the 65 to 85 degree range depending on the time of year, I watch my fishes health to judge water parameters, test kits are a joke and are wildly inaccurate way to expensive for me to use on a regular basis. Since I generally keep my fish in very hard black water i don't us GAC. I did mention growing hog chokers from fry to 10" adults and I did mention keeping cardinal tetras for more than five years when they seldom live more than a year in the wild. I also keep inland silversides which will not live in water that isn't in very good condition. It's an effort just to get them back to the aquarium after collection. Don't ask me any more questions until you've read all my posts.
Michael Hissom
Captive Environments, aquaculture
Test kits aren't a joke provided you're buying a decent kit, following the instructions word for word and the kit is not expired (yes, they do expire). I don't care how many successes you have had with hogchokers, silversides or any other species. If you aren't testing you're water you don't know the condition it is in. Again you didn't give any kind of details to your iridescent shark setup but if you're keeping one in 65F water and the nitrates are high (you don't test so how would you know) then those are environmental factors that will inhibit growth.
I have read all your posts. Perhaps I have forgotten a few details but I'm still aware of the fact that you're leaving out a lot of information that you should be providing if you're attempting to debunk this so called "myth".
It's not radical it used to be considered a fact 35 years ago or so, I've never claimed it works on all fish just some of them and I think it's important to know which ones they are, pacu obviously are not one of the ones that stop growing. I do have theory that so many iridescent sharks are being produced as food fish they have inadvertently created a smaller version of the fish they are culturing. On the other hand this occurs in so many fish I often wonder if some fish just naturally have individuals that never come close to their maximum size.
This is not 35 years ago. This is 2008 and the fish keeping hobby is a fast evolving one. The only people who promote the fish don't grow theory with any kind of regularity are people who don't keep fish or don't do it seriously. The rest of us know better.
As for maximum size there isn't one. The majority of fish are indeterminate growers; they don't stop growing. Growth might slow down considerably but in a healthy environment growth does not cease. Many animals such as mammals stop growing once we reach a certain size. This is not the case with fish.