I have not touched my fish database site in about a year, but it still might help get ideas for larger fish that can live in a 20 gallon tank.
Here is a link of search results for fish with "Min tank length" "equal to or less than" "24". It got 53 hits.
<a href="http/www.aquariumdatabase.com/fishdb_lis...mp;SearchFor=24" target="_blank">http
/www.aquariumdatabase.com/fishdb_lis...mp;SearchFor=24</a>
You can click on either "Max" or "Average" in the "adult size" column to sort the results by those numbers. Click again to reverse the sort order from increasing to decreasing.
From there, you will find many fish to consider, and links to the profiles on this site for more detailed information on each fish.
If you have a 20 gallon long tank, which is 30 inches long - you can change the search for look for under 30 inches.
for a 24 inch it is much as i said, nothing over 4 inches, the Banjo cat being the only exception. and that was the question
so the answer is a Banjo cat at up to 6 inches, apart from that nothing over 4 inches.What is the biggest fish I can put in my 20 Gallon tank?