They can be hard. If you are wanting blue, then get a blue squamosa - more money, but your success rate is MUCH better... even at less than three inches. I got these two blue squammies when they were about 2" about 4-5 years ago. They are getting big now and the big one probably would not fit in a 5g bucket and is quite heavy even in the water. The smaller one is 7 inches of shell. I got the deresa in the photo at about 2"... growing fast too, but not so much lately. I find crocea a bit easier than maxima when small, but they need more light. I would be shocked if the mortality rate of smaller maxima is not 95% plus, but we will never know.
I did get a few Cocos cultured blue maximas but they are 3". I wish that somebody would just keep some of these babies in the south pacific for another season and lets them get to 3" where the mortality would be a lot less. You are seeing this some with Deresa and Squamosa. I guess as long as people are buying 1.5-2.5" clams, then they probably never will.
Even though Squamosa and Deresa are much easier to raise, there is a downside... it always kills you to when you have to rehome them to larger tanks.
Sorry for the bad iPhone pic... and an old iPhone at that...