Lightning Whelk Week on August, 2020: Stocking advice for 40 gallon breeder.?
Lightning Whelk Week 2020. Busycon-contrarium.jpg Lightning whelk
The only non aggressive fish that makes a dent in MTS is the clown loach. You would need several of them, and the MTS would be driven underground, not 100% eradicated and would come back once the clowns got too big for the aquarium, which they will. They are slow growers, so if you start with a school of 6 to 8 clown loaches, it may be six months or more likely a year before they outgrow the tank. You should get good trade in value for them when they are larger.
The clown loaches will get along with rainbow fish which come in the yellows, blues, and other colors you got used to with Jakes. Rainbows are community fish though you will get the rare bad actor. Blind cave fish and their sighted cousins Mexican tetras love hard water and are community fish, with a little attitude. Cherry barbs and rosy barbs, especially the slightly more laid back long fin varieties, are good community fish that love hard water. Zebra danios and other medium size danios will do fine and act as dither fish. Giant danios will get too big and too dominant in a 40 eventually.
You can also try assassin snails. They will eradicate the MTS. Once the snails are gone, unless you feed the assassin snails lots of frozen brine shrimp or similar substitute for a meaty diet of snails, they will stop breeding and may gradually die out. They are actually a fresh water whelk from Indonesia and for a snail, move like lightning.
The sure way to eliminate snails, all of them, and benefit the fish and water quality, is to increase the oxygen content of the water beyond what can be done with air stones and spray bars. That can be done with a somewhat expensive little device from Germany called a Soechting Oxidator. It not only eliminates snails gradually. it eliminates algae and turns detritus in the tank to a light colored low volume "ash" and destroys the free swimming stages of many fish diseases and parasites. Too bad it costs at least as much as many filters, which it does not replace. It also turbo-drives your filters which become much more effective. If it weren't for the price and the chore of recharging it monthly which involves food grade hydrogen peroxide, we'd be importing lots more of these from Germany.
Kribs are West African, and come from soft acidic rivers, not the hard water, limestone regions of the East and the Rift Lake valley, so your substrate would not be welcome to them. Even the hard water loving to brackish cichlids of India and the cichlids from Madagascar are not community fish.
Next time you try jakes,(Alonocara jacobfreibergi), make these changes, at least a 75 gallon tank, and preferably larger and six feet wide, like a 125 or 150. Start with a group of a dozen in a 75, or more in a larger tank. When the first males appear, pull out the biggest dominant ones and trade or sell them. The sexually precocious males are also the most aggressive, more interested in fighting than in mating, and tend to be ultimately smaller and not necessarily the most colorful males even though they start out impressive. Once you have "culled out" a fourth of your fish, keep an eye on which ones remaining are males. Try to save two, one in reserve. I usually put him in a divider in the end of the same tank. Once in a while, I trade the males so that they never get too bored with having a harem. This also increases the gene pool of any fry I obtain, and maybe raise in that 40 as a grow out tank or some other tanks if you have a market for them.