Eating the 3 neons in 2 days should not hurt your bichir, but I would not make a habit of adding small fish to the tank. Also beware, angelfish are known to eat neons as well.
If you post a pic of your catfish we can help you get a proper ID for it. Knowing what species you have in a tank is extremely important. It is impossible to know you are properly providing for an animal if you don't even know what it is.
I am wondering how long until you move these fish into a larger tank? The bichir is a member of the polypterus family, and are not a community fish. Ploypterus senegalus, which is what you have, average about 20 - 22 inches full grown, and they also get quite thick in body. If you watch your fish closely you will see how wide the mouth opens, and these fish are predatory. Anything that will fit into its mouth is likely to become food. Minimum tank size for just one of these is 75 - 90 gallons, depending on how much maintenance you want to do. At 5 inches long, it is already nearing an end to fitting safely into a 30 gallon tank with other fish.
Angelfish also get quite large, so will need a larger tank soon. Both species grow quickly. You don't say how many angelfish you have, but let me offer an example for you. My last group of angels came in about 5 months ago, they were dime size and there were 6 of them. They went into a heavily planted 65 gallon tank and were the only fish in that tank. 3 months later they had to move to the 90 gallon because they were too large for the 65. Now, 5 months after getting dime size angels they are each the size of 1/2 dollars or larger. This is normal healthy growth rate for an angelfish, and these 6 are only about 1/2 grown. Angelfish can reach 6 - 8 around inches depending on their species. Wild caught and purebred scalare and altums can get up to 10 inches if healthy.
Kissing gouramis will also get large... 8 - 10 inches, and the Blue Gourami
will average about 5 inches when adult. Depending on the species of spotted cat, between it and the bichir, the cory catfish may at some point also become food, as will likely any remaining danios.
I hate to say it, but your tank is already over full, even if all of these fish are juvies. Instead of shopping for more fish, I would strongly suggest shopping and saving for a much larger tank very soon. With the fish you have currently, 90 - 125 gallons would be a practical size, depending again on how many angels you have.
Because of the species mixture you have, I would also suggest making sure you have an extreme amount of deocration in that tank to avoid territorial aggression. Floating plants and plants (either live, silk, or plastic no matter) that are very tall to help break up the upper 1/3 of the tank will be especially important for the angels and gouramis to maintain a safe relationship without fighting over territory. Extensive caves both big and small will help keep your catfish and bichir compatible for longer without issues, as these 3 will all be sharing the same lower 3rd of the tank for territory.
Hope this helps.