Here’s a nice description of why, in this study, morphants are preferable to mutants.
"To determine whether Par-3 is involved in polarizing the dynamics of Notch signaling endosomes, we disrupted the activity of the zebrafish orthologous gene pard3ab (theretofore referred to as par-3) via microinjection of a well-established antisense morpholino oligonucleotide (MO) (19, 20, 41). Despite the fact that a maternal zygotic germline pard3ab knockout has been previously generated, it has grossly normal brain morphology and survives largely to adulthood (42). This phenotype is distinct from defective brain morphology and abnormal proliferation/differentiation states observed in the morphants, suggesting that genetic compensation (43) is at play. Therefore, this knockout line is deemed unsuitable for our study."
Zhao X, Garcia JQ, Tong K, Chen X, Yang B, Li Q, Dai Z, Shi X, Seiple IB, Huang B, Guo S. Polarized endosome dynamics engage cytoplasmic Par-3 that recruits dynein during asymmetric cell division. Sci Adv. 2021;7(24):eabg1244. doi:10.1126/sciadv.abg1244