The end of his tail has just begun to turn red.
Red margin on the tail can be found in individuals in all populations of Tusks...
Tusks coloration is highly variable between individual specimens. Contrary to hobbyist myth and popular marketing most variation is not due to collection location but more to condition, dominance and individual characteristics. Unfortunately it is hard to command large dollars for a higher likelihood of health and longevity that comes with well collected specimens than it is to get people to drop dollars for bright splashy colours...so the myth is perpetuated...
Now all you hear about when someone has a beautifully colored Tusk, is how it must be an Aussie that was mis-priced or labelled wrong...and again the myth is perpetuated...
A brilliant specimen is a brilliant specimen and is in itself rare and special and they can come from either locale. With Tuskfish especially WYSIWYG is huge and what really matters. The risk is that a vibrant Indo specimen that was collected with cyanide (cyanide poisoning deepens all fishes colours BTW) will sicken and die usually within a month of going in your tank for no apparent reason although it can take longer...
Tip: if you are looking at an Indo Tusk, look for hook damage in the lip (not bashing damage to the mouth due to poor handlin) any fisherman can identify that type of puncture on the upper lip or side of mouth... As long as it is healing cleanly that is a guarantee that it was collected with a baited hook which is the best for these fish.. no nets, no cyanide, no dynamite...