There's already one or two forum topics with this question, try searching for "Tuna". The first result I found on the topic is pasted below:
"They can have salmon or tuna, also--but it has to be fresh. Canned foods like that have too much salt, so you need to buy the actual fresh fish at the supermarket." --Zalea
"They can have salmon or tuna, also--but it has to be fresh. Canned foods like that have too much salt, so you need to buy the actual fresh fish at the supermarket." --Zalea
