Winter & Summer Months, it is best to fish Murray Cod during warmer months as they feed on baitfish, yabbies, shrimp and surface bugs which are in greater supply during warmer months, so if it's cod your after you will increase your chances in the warmer months of the year.
Water Temperature, when water temperatures begin to warm up, spring species like bass start to feed and get on the move, species like salmon disappear into colder waters.
Time Of The Day, When the midday sun is at its highest and light penetration is most glaring, fish may hide away, so early morning or dusk are best, and an overcast cloudy day can give a angler a good days fishing.
Fishing Depth, A good depth finder is your best friend in this circumstance, different fish species will be found at different water depths due to different water temperatures.
Retrieving Too Fast, Sluggish fish need to be compelled to strike, and jiggling a live bait or spoon bait will attract a predator and give them time to bite.
Wrong Size Bait, In my experience no big bass will strike a large swimbait, sometimes a small reduction in bait size can make all the difference.
Location, Large open areas of water with little or no cover won't be as good fishing as an area of water with weeds, reeds, logs and trees.