Steve,
It lookslike uo have an Atwwod aluminum tank with brass to PEX adaptors. If the leak is between the tank and the brass, where you see the white thread sealant, then remove it and reseal with tfpe tape or paste. I prefer Harvey # 55 yellow teflon tape, rated for gas and high temps.
Should it be the PEX adaptors, a minor tightening of the nut should do, do not over do it, the back parts of the plastic nuts break easily if over tightened . They have a neoprene cone shaped washer that seals very well when aligned properly.
Max