I've moved the fish that were in a 20 gal to a friends tank that had the extra room for them and I new they were going to have to moved into a bigger tank in the near future. Having changed my mind on more tanks I thought they would be much happier with more swimming room. I've also decided on the fish I want to keep in this tank as it looks like it'll be my only one. The fish that moved out were some tiger barbs and serpae tetras for now. There is still a red-tailed shark in the 20 gal but part of my question is will he be ok with the fish I want to add. I want to add some guppies and dwarf gouramis and my first question is would they be ok with the shark? The next question is that since the tank has been up and running with all the fish for roughly one month now, do I still need to intro small numbers of fish at once or could add all the guppies and then later the gouramis or even all at once. The tank has had a 20% water change since the fish were removed but the filter has lots of bacteria built up and the water is testin good. Any thoughts on the combo and intro would be great!! I should also note that the shark could move top the other tank aswell since he will get to a fair size but if he works that'd be great too.