Senegalus after they reach 4"-5" tend to grow slower. Albinos usually do the same you won't really notice the growth unless you do a before and after. They also seem to get fatter them have a growth spurt. I have had a couple that get fat then grow into it and it makes them look thin then they'll start the fattening process again. Just keep up with the varied diet, water changes and keeping him healthy and he should grow fine.