Heteroscedasticity might not be a real problem here. Variables such as weights and lengths are typically not very skewed. ANOVA is quite robust to mild non-normality and might be perfectly fine. Heteroscedasticity will cost you some power in K-W analysis, but inferences will remain valid. Try both ANOVA and K-W. If you get similar p-values, you're fine. Otherwise, you should look more closely at your data for outliers, subgroups, etc.
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