Hi and welcome
Which country are you in?
Please be aware that a pair of boars needs a 2x5 ft cage as a
minimum welfare recommendation. Guinea pigs are ground roamers and need all the space they can get to run around and stay healthy in the long term. Too small cages also encourage bloody fights as the loser of a dominance battle has nowhere to escape, as they would normally do after a fall out.
Here is our housing information, which contains information on traditional as well as C&C grid cages and alternative forms of bedding:
Housing, Bedding & Seasonal Care Guides
Please give your boys some huts in a bigger cage, even if it is just a couple of cardboard huts or tunnels. Guinea pigs are not wired to live in an open space.
Boar quartets don't work so you need to keep your piggies in 2 pairs in separate cages. If the new pair is not in good state, please quarantine them in another room and have them vet checked. make sure that you have got the money to pay for any necessary vet cost so you don't become the next owner to fail them.
A Comprehensive Guide to Guinea Pig Boars
Adding More Guinea Pigs Or Merging Pairs – What Works And What Not?
Boars: Teenage, Bullying, Fighting, Fall-outs And What Next?
Please make sure that you sex all piggies upon arrival; mis-sexing is much more common than it should be. If you adopt from the free-ads, you have to be aware that people getting rid of problem pets will go to great lengths in order to do so and will be extremely economical with the truth.
New guinea pigs: Sexing, vet checks&customer rights, URI, ringworm and parasites
I can't see much hay in your cage; an unlimited supply is the mainstay of any guinea pig diet. It should make around 80% of what they eat in a day in order to prevent health problems from malnutrition like overgrowing teeth, digestive and other health problems and a shorter life span. A limited amount of mixed herb and preferably green veg and 1 tablespoon of pellets per piggy per day are more daily additions to the basic diet. Fruit and tomato as well as high sugar veg like carrots or sweetcorn should only ever be occasionally extra treats in small quantities as they are too sugary and too high in acid and can cause potentially fatal health issues (lip infection, bloat).
Here is our detailed diet information:
Long Term Balanced General And Special Needs Guinea Pig Diets
Seeing your how you are keeping your existing piggies, do you really have the space, means and experience to deal with more piggies that come with some major potentially expensive problems?