Definitely more then one lol! Wow that’s a big ass tank, I wouldn’t go less than 5 plants. Maybe look for good deals on Etsy, eBay, and Amazon. I’m pretty sure I saw a decent deal while window shopping earlier.

Edit: something like this-> https://www.amazon.com/Planterest-Sagittaria-Subulata-Freshwater-BUY2GET1FREE/dp/B07H6CH5DV/ref=asc_df_B07H6CH5DV/?tag=hyprod-20&linkCode=df0&hvadid=309951030128&hvpos=&hvnetw=g&hvrand=7632751718926919584&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9007321&hvtargid=pla-636552641201&psc=1&tag=&ref=&adgrpid=60883531599&hvpone=&hvptwo=&hvadid=309951030128&hvpos=&hvnetw=g&hvrand=7632751718926919584&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9007321&hvtargid=pla-636552641201