First off just need to vent:
I know some people here in the forum have not entered the working world yet but some rules apply to dealing with business about ANYTHING. If it makes good business sense, saves them money by both products and wages spent, and is a better way then the company is doing things now, they might just implement whatever it is you want to change in their company. Being mean or angry with anyone you are dealing with, in a business, or even with customer service.... will
: GET YOU NO-WHERE FAST! BOTTOM LINE!!! That same rule applies to a lot of things in life. - I just needed to state that.
Accumulating a lot of bottles in the OP. I looked up a nice shelving unit after re-evaluating how I want to set up my fish. At the moment I decided I want to use this:
It's a 4 shelf Sandusky 48W x 74H x 24D unit able to hold 800 lbs per shelf. It will hold the 29 gallon grow out tank I have, up to 4 10 gallon tanks, (On another lower shelf.) top shelf would be deli cups shelf below that just might hold some of the smaller desktop aquariums I already own and are spread around. However I need to see if the two top shelves could be used without danger to me LOL!! I don't want to fall off the step stool. I may just put plants and supplies up there. I would need to see and play with the unit before deciding 100%. It's available for about $150... which isn't that bad a price for what it can hold. Even if it doesn't hold fish forever, it's rated safe for food storage and is an all around good investment IMPO.
This shelving unit is also JUST as big as a 55 gallon tank long-wise. It may just be big enough to upgrade the growout in the future... but the measurements may include the posts sticking out at the sides and the 55 might not be supported correctly.
The biggest problem using a shelving unit for breeding betta fish is
WEIGHT. This shelf might support more then my tanks can produce... I'm not sure my floors can in some spots!!! I need to look around and decide if I can put this in a spot that won't cause my house to fall apart and still allow me to maintain my fish easily. Our mud room would probably support this but it would get drafty and cold in the winter.... hmm.
Sandusky 48"W x 74"H x 24"D shelf= 74lbs
10 gallon leader tank= 20 1/4" x 10 1/2" x 12 9/16" Weight full: 111 lbs x4 = 444 lbs.
29 gallon tank= 30 1/4" x 12 1/2" x 18 3/4" Weight full: 330 lbs.
32 oz. Betta fry deli cup= 8.34 lbs each (not including cup weight since I have no idea).... guesstimating 50 on the shelf/shelves... Weight full: 417 lbs.
hmm maybe..
1 gallon tank weight = 8.38 lbs... x 2 = 16.76 lbs...
1 1/2 gallon tank weight= 12.57 lbs x 2 = 25.14 lbs
5 gallon tank= 16 x 8 x 10.. Weight full = 62 lbs...
2 1/2 gallon tank weight = 27 lbs
(some of these figures came off charts online because I didn't feel like doing math.)
74 + 444 + 330 + 417 =
1265 lbs....
GAH!

Well over a TON..... *grumbles* Thats just the shelf, 4 -10 gallons, 1 -29 gallon, and 50 betta cups.. not including the weight of the actual plastic cups themselves sitting on one spot on the floor..... I'm so not sure any floor in this house but a concrete slab will be able to take this kind of weight....
Then again I don't know what the average floor in a 60 year old house can hold on average.... I'm not sure how I could find out IF the floor could hold such weight either.....