First I would like to welcome you to MFK. I think it's great you love monster fish. We are here to promote as well as educate members on the proper care and husbandry of these fish.
All three species (you don't specify what species "shovelnose" you have) are freshwater giants. The tanks are too small for all but very young fish and with proper care will out grow your tanks in a very short time.
As adults they would require (on the low side) an enclosure about 12' x 10' x 4' which is around 3600 gallons. In addition to swimming pool size filtration, then facture in the water bill, electric bill and the cost of feeding these monsters and you see this is nothing short of a massive undertaking even at the minimum requirements.
People often buy these fish with the idea of re homing them once try get too big to care for. This is not as easy as it sounds. Local fish stores don't want them unless they have someone to resell them to as they require too much space and cost too much overhead to keep for any length of time. Public aquariums get far too many requests like this and 99% of the time they will not take them.
If you're interested in predatory catfish do some research and find species that grow to a size suitable to the home you can provide them, both you and the fish will be much happier.