I work with zebrafish adults and larvae and am trying to characterise mutations from CRISPR and ENU mutants. I either extract the genome from entire larvae between 3 and 5dpf or adult fin clips. So far I've been using the NP40 lysis buffer with ProK. However, the quality of my PCRs (both experimentals and wild type) is just about ok. Lately though, I've been getting smears when I run my PCR products on a gel. I tried a professional kit (PHIRE) and noticed a significant improvement in the quality of my PCR. However, this kit is very expensive and not cost effective as I have to go through a lot of fish. Is there an alternative buffer that I can try? Also, does NP40 buffer go off after a period of time? Thank you.