They can be aggressive, but if you give them enough room they're fine. I have 2 in a 2 gallon tank and they do just fine. If you have "stuff" in the tank that they can use as boundary markers...that helps. They also like caves. They use them to breed in.
I've set up a new tank for my gobies. It's a 5 and not brackish yet, but I have the marine salt and will be bringing up the salinity a bit at a time once the plants and gobies settle in after the big move. My crypts are probably going to melt on me.....I always do that to them...lol. As soon as they get used to a new spot and just start growing nicely and spreading out....I go and move them again !
Anyway...the gobies are checking out the new quarters, following each other around like a couple of puppy dogs. This setup isn't entirely what I imagined, didn't really plan on that fake rock thing, but it'll do for now until I find a REAL rock I like....I really wanted a grasslike plant but I think all of those would need high lighting and I'm not planning on using a whole lot of wattage over this tank. Just have a 10w screw in cf. I'm also going to get rid of that intank whisper...hate those things. Next time I get to WallyWorld I'll pick up a small aquaclear HOB. I also have a RedSea HOB nano filter on it as well. I'll keep that there as an extra incase I need a seeded filter fast...you just never know !
I have read on a couple of sites that crypts and java fern can tolerate BW....I guess I'll have to find out for myself it that's true or not. I hope so, because I really like live plants in my tanks.
Here's a few pics. I JUST finished setting this up so it's still a bit foggy.
