5 cm! I envy you. I want something that small. My senegalus was a little larger than that when I got him - 6 cm. You can get him started on omega one sinking shrimp pellets. If you're bare bottom, I'd snap pellets in half before dropping them in. If you have gravel (like me) just drop them in whole. The pellets soften a bit and the small bichir should have no problem biting chunks off.