Don't be discouraged......I have a pacu that I raised from a quarter size....he/she has the best personality and is worth all of the aggravationJust my personal opinion
Your Pacu is 29"?! Please post a pic of this beast.
Both you and OP should not waste any money on plants and start saving up for larger tanks. I don't even know what size OPs tank is, but I'll go out on a limb and say it's too small.