I am a longtime zsh user and tried fish earnestly for a month or so, but gave up because I could not figure out how to ignore certain patterns while auto-completing filenames. For example, I typically edit tex files and I don't want any of the temp files to be suggested as autocomplete suggestions. In zsh, I can write

zstyle ':completion:::(vim|nvim)::files' ignored-patterns '*.(aux|dvi|log|thm|idx|pdf|rel|out|tuo|tui|tuc|tmp|mpo|mpb|mpd|1|keep|pgf|fls|gz|fdb_latexmk)'

(yes, tex generates so many temp files!) I couldn't figure out how to do something similar in fish