So I have two chiuaua/feist mixes. They are really sweet dogs but lately, they have both developed food aggression. Not towards people but towards each other and sometimes the cats. It's mostly towards each other. But it isn't all the time. Sometimes they eat together without any problems. And other times they are aggressive. Now, when i say aggressive I don't mean they outright attack each other. Mostly they growl or sometimes even snap at each other. The girl is the worst one. It has gotten to the point where the male dog won't go near the food when the other animals are eating. I've started having to feed him separately. I've been trying to get them out of doing this. Feeding the two dogs separately works sometimes. But other times, the girl dog will go between the two food sources and snap at the male dog whenever he goes near either one. Should I start feeding them in separate rooms? I've never dealt with this problem before.
First of all if you have cats in the house you should place their food in a higher place, cats are great climbers and will feel much safer especially with their food in a higher place the dogs can't reach. As for the dogs, when did this start? did something happen that caused this to start all of a sudden or has it always been that way? I'm not sure if separating them is the best solution for the long run but it's definitely a good idea for now until you find a solution.
The dogs have shared their food, ever since we got them, and it hasn't become a problem until recently. My brother in law does tend to play rather rough with them so I'm thinking maybe that is causing it. I've told him to quit playing so rough with him but he doesn't seem to get the point. But no, the food aggression is new. And it isn't all the time. It is just some of the time.

This sounds like they're fighting for dominance which should never be happening because YOU and the members of your family are supposed to be the alpha dogs (pack leaders). If not corrected, this may grow into more serious possessive behavior like protecting the food, toys, the couch and whatever the dogs think to be 'theirs' from you and the members of your family. Feeding them separately will seemingly solve the problem but it doesn't address its cause so it's very possible they'll keep fighting for dominance in other situations. What you really need to do is to work on becoming a pack leader for them both.

A few simple tips are below.

In the wild, the alpha dog always eats first so your dogs should ideally be fed after you have eaten.

Establish routines for feeding and other activities. Always use the same commands, times and places for the same activities. Feed the dogs at the same time every day, at the same place, and teach them to obey simple commands like "sit" and "wait". It's also a good idea to teach the dogs to obey "leave it" command.

Do not start feeding the dogs if they're overly excited or tensed. If this is happening, ignore the dogs till they are calm.

After the dogs have eaten, remove leftovers. If there's no food, there's no food aggressiveness.

Whenever you communicate with the dog, you should remain calm. If you get nervous, the dogs will feel your emotions and become nervous too, which can result in more aggression.

Keep in mind that your dogs's unwanted behavior like snapping, barking, growling is actually rewarded and therefore reinforced each time you back off. You should be consistent and persistent.

Give the dogs a good amount of mental and physical stimulation every day to drain their energy. Dogs are usually much calmer and more balanced when they are well exercised.

Rough games are not a good idea in my opinion because they stimulate aggression.

You can find some useful information here as well:

Feed them separately. My dogs are food aggressive and one eats so fast that the other cannot keep up. So I feed in separate rooms.