C.V.
Absolutely.
Be sure that your cat has plenty of fresh water at all times. The most important thing is to ensure that kitty is urinating enough.
No more food or treats that are fish-based. These have high magnesium levels, which cause urinary crystals that block the urethra.
Switch to a low-magnesium foor for feline urinary health. Purina One makes such a food that you can buy in the store. Here's a link: http://www.purinaone.com/products/cat-food/smartblend-uri.... It's your cheapest option. They also sell a wet-food version.
Your other options are sold by your vet. When my old kitty started getting struvite crystals, our vet sold us a bag of Iams urinary health blend (can't remember exactly which one). The cats WOULD NOT eat it. They hated it. So I switched to Purina One. They liked it much better, but didn't seem to enjoy it. Finally, a friend of mine works for Royal Canin. He brought me a bag of Royal Canin Urinary SO. OMG...it's like cat crack. The cats love it, and they're getting the healthy, low magnesium food they need. So we've stuck with that.
Here is a link to foods for feline urinary health.
http://www.amazon.com/gp/search/ref=sr_gnr_fkmr0?rh=i%3Ap...