Help with new fish

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So my grandma was moving but she had 2 angel fish, 3 corycats and a pleco. The angel fish sadly passed from stress or something and grandma got sad. I've been looking into tanks for a year now and I luckily set up my tank in march and it's ready but I've been looking into getting a beta and chili rasboras. My grandma gave me the corycats and pleco, thank god it only grows to 6 inches, but I have them in a 10 gallon tank which is very temporary. I'm getting a 20 gallon on may 10th and properly setting it up. I know NOTHING about these fish but I want to take care of them. Any advice or tips is amazing!