Howdy ya'll. First time poster but I've been reading this forum off and on for some years. I'm going to apologize now because I think this is going to be a long post. Any veteran aquarists that read through it and can offer suggestions I would be greatly appreciative. A little quick background: I've been obsessed with aquariums since I was about 10 years old and repeatedly murdered random schools of tetras trying to keep them in 10 gallon tanks. I've been keeping aquariums for over 20 years but cut back about 10 years ago to a single tank. Recently we bought a bigger house and I finally have the room (and stability) to stock large tanks again. I am cycling a 125 gal long tank (22"L x 72.5"W x 23.375"H) in my livingroom. I want to make it as perfect of a self-contained eco-system that I can so the plan is to introduce species from the bottom up to create a nice balance. I know what roles the species in the tank need to play but I'm having a hard time deciding just what species to use. The plan for the tank: Substrate sandy (undecided just what type yet) Medium density planting with both ends heavily planted Some flat rocks placed among heavily planted areas to offer spawning grounds Cave system made out of halved clay pots glued together with aquarium silicon and covered in moss for realistic look rear-center of the tank (possibly might make several smaller cave systems instead of one big one). Large piece of driftwood possibly mounted to the top of the tank if I use too much ground space up. Mechanical/biological filtration undecided yet but most likely a canister filter, powerhead, and a DIY CO2 rig. water temp around 80 degrees, ph 6, soft soft water Once the tank is cycled and planted I want to start by adding Malaysian Trumpet Snails, a small schooling fish that breeds rapidly, and a shrimp species that also breeds rapidly. Once those 3 species become established and are comfortable and breeding on their own I want to add a school of panda corys (10?) After the corys I'll add some ram cichlids (4-6?) And then I'll add 2 jewel cichlids. I know that eventually the snails will get out of control. Once their population is deeply established and bordering on infestation (probably a year or more away) I'll add some assassin snails - and once the assasin snails are well established I'll add a small snail eating loach or two. The idea is to have a tank where each species is happy and thriving and able to breed but whose numbers are kept in check by the other species within the tank. I did something similar with Oscars and convicts in a gigantic 8'x3'x4' custom tank years and years ago but there is a significant difference in tank size here. (by the way I've read probably a dozen posts here that suggest oscars can live in smallish (55gal) tanks because they don't really get 12" long and I can say that that is 100% NOT true! I raised 2 oscars from babys that reached 16 inches or more and rescued two other oscars that were already 10 inches out of a 55 gal tank and BOTH of those rescues also grew to about 16 inches before I sold the tank). So my big questions: 1. The shrimp. I'd like to use something colorful and attractive but it needs to be a rapid breeder that can outpace consumption by a few small cichlids - I'll make sure the shrimp have PLENTY of hiding spaces (I'm considering using pvc or some kind of tubing to make a super-cave structure that can sit in one of the extremely densely planted corners for the shrimp to use). Suggestions on the shrimp? 2. The rapid breeding schoolers. What to use? Simple guppies could work but while they breed rapidly they only have a few offspring at a time and might not be able to outpace consumption by the cichlids unless their school is ridiculously large. I was thinking rosey red minnows might actually be fun- their color will contrast and they have large broods which should be able to outpace consumption and I could probably get away with keeping 20-30 in the school but I have 0 experience with them. Mollies or Platys? I think they would be too big for the adults to get eaten by jewel cichlids so they could live a happy life and breed away with the occasional offspring surviving to replace the occasional death as the school ages BUT I've had mollys get 3 inches long and I want a small schooling fish. Anyone have a suggestion? I'll still be feeding with flake/pellet/brine shrimp/worms on rotation. The idea isn't for each organism to exist as the sole food source for another - just that they are able to breed and a few offspring survive to replace the aging parents but numbers are kept in check. 3. I inherited a 30 gallon tank with a school of 10 tiger barbs, 1 angel fish, and a clown loach about 3 months ago. The clown loach I am expecting to have to rehome eventually (he's about 2 inches now and thinks he's a tiger barb though so he's too amusing to part with yet). The angel is maybe 4 inches long. I'm considering putting him into the big tank too and just letting him live out his life there but I have no experience with angels - is he going to screw up my eco-system? Is he going to be happy there or should I rehome him? 4. I want to keep bioload low but does anyone have any suggestions for something else that can be added to the tank without upsetting the balance? I was thinking maybe some hillstream loaches? Or maybe a small breed pleco or two. I would love to have a school of ottos in there but they wouldn't like my water temp I don't think. Dario dario? I'd love to add a few of those guys in maybe before the ram cichlids but I've also never had this species. Instinct tells me that there will be plenty of room for two pairs of them to stake out a territory in a 6 foot long tank with only 2 pairs of rams and a pair of jewels but I'm just not sure. Also what are the chances the jewels eat them? Maybe go with 10 dario dario and 6 rams and no jewels? But then if my rams over-breed who will eat their excess young? Lastly, does anyone have some malaysian trumpet snails they can send me? I found a few for sale online but they seem to be going for about $1 each even in bulk which is just crazy for a rapidly breeding pest snail. Appreciate any input - even if its not directly relating to a question i asked.