Hi I’m Julie I’m new to fish keeping. could someone give me some advice please. I have a 12 litre tank with foam filter a 5 month danio and a 3 month old platy but the last couple of days I’ve noticed the danio struggling to swim up in the water and wondered if maybe he has swim bladder disease- I feed them flakes, bloodworms occasionally and they have had brine shrimp but don’t tend to like it. What can I do to help my young fish as he I struggling. I also have a main 35lire tank with 4 danios and 4 platys. The two in the small tank are what I have rescued from the main tank