Although I have no experience with the above vendor, I must say.....
Growth rates have everything to do with how fish are kept, and not much to do with the vendor. If water is changed once per month, growth rate will be slower than once per week, just as growth will be slower if water is changed once per week will be slower than every other day. This is especially true for young fish.
And
Minor deformities are also more prevalent when buying very young fish/small fish because many deformities don't become obvious or apparent until fish are older/larger, especially when raising large schools of fry.
When I buy very for example 10 young fish, I am not surprised when 1 or 2 will exhibit some minor deformity.
For me the deformed ones usually become feeders, and are never used in breeding.
