I just had 5 zebra hermit crabs. 2 of them molted recently. Today, I just bought some shells for them, but they didn't seem interested. Just earlier, one of the crabs ate another hermit crab! I am super angry and heartbroken! Now I have only 4! I also didn't feed the tank today to avoid any issues with water parameters (I have a 10 gallon). Is this normal for them to eat each other? Is there a solution?