Yes, Pension credit is means tested ( I get it ) you have to claim all POSSIBLE sources of income ,even if you are not actually claiming them (a private pension for example that you could claim but have chosen not to)and all money in cash or ANY type of bank account.
If you have a possible source of income that you are not claiming (like a private pension as I said above) they will take it into the calculation as though you are claiming it in full even if you have not actually claimed it.
There is a pension credit helpline who are very good and can explain it all.
But do not try to fool them they can see what pensions and accounts you have even if you try to avoid mentioning them !
If you make a successful pension credit claim they will send a representative round to your home to interview you ( I had this) you need to have all your financial details ready for them to check.