My first Betta...some questions...

[DragonFish]

Haha, I'm not sure of I'd call a 3.5 gallon huge myself...its even too small for a stable cycle still...but, it is perfectly adequate as a permanent home for a single normal long-finned male betta. ;) I'm sure he'll adore his new home.

Just a tip...if you're getting a kit that comes with a filter or something, you can go ahead and ditch it. In such small tanks, the filter flow tends to bother bettas a little more so....and since its difficult to cycle such a small volume of water, a filter is pretty pointless anyway. Just keep up with a couple weekly water changes(at least 1 50% and 1 100%....though an extra 25% tossed in there might not be a bad addition either. I've always found my boys to be more active and brighter with at least a slight extra water change in the week in my smaller tanks)instead. ;)

As far as artificial decorations go....
Steer clear of plastic plants. Even the softest always run the risk of snagging and tearing fins. Go with silks. Much softer on your fish's fins and they're often much much 'fluffier', giving your betta more cover(which is something most any betta will always appreciate)and offering them something more to rest on.
Personally, I'm a big fan of Petcos silk plants....for the price, they seem to have the nicest/fluffiest selection. With a couple of their plants, it won't be hard to fill up a 3.5.....just make sure at least one plant is tall enough to reach/get close to the top of the water. ;)
Caves can be just about anything you like(thats proven aquarium safe, of course). Just feel it and make sure theres no really sharp edges that could snag your guys fins. If you want to save a little money though, this is definitely where you can do it....a little terracotta pot from the craft store(less then a buck)can make an excellent cave. Just be sure to either knock out the bottom or plug the hole with some filter sponge/aquarium sealant/make sure its well covered by substrate if you can and you're good. You can also use glass cups or even coffee mugs, just be sure to rinse very well(which is something you should do with anything you add to your tank anyway)in hot water/soak well in hot/boiling water and rinse rinse rinse if used/exposed to soaps and such.

As far as live plants and such go....well, I'm not really he best person to ask I'm afraid. I have the worst green thumb ever....I kill bamboo xP Can't manage to keep any aquatic plant alive either besides some hardy non-rooted plants.
If you really want to look into live though, a 3.5 would make an awesome nano NPT. Take a look at this thread....it'll explain things a little better: http://www.bettafish.com/showthread.php?t=114575
Also, the planted tank section of our forum in general has some awesome info. Its definitely worth going through even just some random threads and reading over what they have to say. http://www.bettafish.com/forumdisplay.php?f=147

[AyalaCookiejar]

I just got some aquarium safe silicone for about $4 at menards the other day. It's great for filling the holes in those terracotta pots, covering any sharp edges and also for making your own decorations. Many people make caves and stuff out of rocks or marbles with the aquarium safe silicone.
And I over decorated my 10 gallon with like 9 of those silk plants from petco for my sorority. They have nice 3 packs of silk plants, and I have both the midground and background 3 packs. I think those three pack midground silk plants would be perfect for a 3.5 gallon..

[BrittanyAndIroh]

Ugh, guys...I got his new aquarium and I don't think he likes it. He's not really eating now. Do you think it's just the shock of change?(bigger tank, different plants) I'm kind of freaking out here.

[AyalaCookiejar]

I don't think so. Usually they get curious and territorial about new surroundings. How did you acclimate him to the new water?

[BrittanyAndIroh]

I made sure his water was the same temp as his old water before I moved him over(via sticker thermometers), and I've made sure his water has been between 75-80 degrees since then, so I think he should be okay. He seemed to be okay the first day, but then yesterday I moved his tank to about 4 feet away, and he's acting funny. See, he was on my computer desk where I spend about 80% of my time, but I moved him to a bookshelf a few feet away from me, and now he seems depressed. Could that happen? Do fish get depressed? It would make sense to me considering he was with me at my desk from the day I got him (a month ago), and he's used to having company.

[jenjen182]

Hmm, fish depression? Well, I suppose fish could be sad- he probably enjoyed spending time with you. Betta fish like to see the action; they love the drama! He probably loved being out in the open with you. I would consider moving him back there; there is no other reason why he would be depressed!

Keep up the great work! :D

[AyalaCookiejar]

Yes, they can get depressed and they do like company and attention as well. Mine all greet me at the front of the tank (except for my blind fish, lol, but he always swims over to check it out when I wiggle stuff in the water or blow on the water surface). They like to watch me and follow my fingers around.

[BrittanyAndIroh]

Maybe I'll move him back if he doesn't get better. He's hanging out at the top of the tank, which makes me think he is sick, but he isn't just sitting there. He'll hang out in one corner, then move to another, then another. Maybe he likes the top cause its warmer from his light?

[AyalaCookiejar]

They generally do stay near the top often because they get air from the surface, but they generally aren't ALWAYS near the top. This is why I always suggest tall plants that reach the water surface so they have places up there to rest.

[crowntaillove3]

Welcome to the forum! Mine actually stay closer to the bottom, even though they move around all the time. As for your previous heater dilemma (for future reference they really are like potato chips, even if two is all that you can have) make sure to check the thermometer before you put in the heater. The temp in my two tanks are both 80* without heaters. Good luck betta keeping! Could you post pics? We love pics here!