Hi there,
I have a fluval chi with a betta in and have had it for over a year now, but not without problems. I will let you know the issues that i had and the lessons i learned as i was new to this. The people on here are great for answering any questions you have no matter how simple they may appear.
1. The LFS gave me just a 25w heater which i couldnt regulate and it wasnt good enough for a chi, temp never got up above 24 degres. I live in the UK so the weather is not that good. I changed it to a fluval 50w heater with a temperature display and now its at a steady 27 and my betta is much happier.
2. Due to the low temp and only doing pwc every week (i know much better now and have learned my lessons) my got sick. He got swim bladder disease, all better now thanks to the help i received from here.
3. Change 10 - 15% of the water every 2 days and your fish will thrive, keep it warm and he will thank you for it by interracting with you a lot.
4. I feed him the Hikari Betta Bio Gold pellets and he loves them.
The fluval chi's are a very good looking tank to house your fish and with the right care you and the fish will love it. I cycled the tank for a few weeks and had no issues in acclimating him.
In a nutshell, keep him warm and PWC, PWC, PWC, PWC every couple of days
and all will be well.
Any questions i will be happy to share what i have learned on here. Hope this helps. Enjoy your fluval and fish.