CARP numbers have exploded since last summer's floods across southeast Australia.

Numbers are up by an estimated 4000 per cent on last year and many recreational anglers have dubbed carp levels the worst they've ever been since the species was introduced in the 1850s.

But despite the high number of carp, and reports last year of native fish being decimated by black water, anglers remain positive about the outlook for waterways.

Jim Credlin, owner of JC's bait and tackle at Swan Hill, said there were huge numbers of shrimp and yabbies in sections of the waterways.

"Carp have gone ballistic in all the river systems," Mr Credlin said.

"There's plenty of feed for them. People say they're not catching them and it's because they've got plenty of food.

"There are plenty of yabbies and plenty of shrimp in the rivers so they're going to be harder to catch compared to if they were hungry.

"In the Edwards River, at Moulamein, over the Christmas and New Year period there were Murray cod caught in the vicinity of under size up to about 75cm.

"Even between Kyalite and Moulamein in the Wakool River we're hearing of cod being caught, some under-sized, but some around the 60cm to 65cm mark.

"Further along in what we call the pool water there are some large cod being caught in the last three or four weekends up to a metre long."

Mr Credlin said redfin and yellowbelly fish stocks were also in good supply.