missouri's aquatic hobby and conservation organization

the MASI SWAP

The MASI Swaps are local sales, held three times a year, in which independent vendors, clubs, and local businesses can offer hobby goods and animals to visitors.

Things you may find at our SWAP include fish, aquarium equipment, tanks and more! As well as amphibians, isopods, reptiles, springtails, aquarium plants, carnivorous plants, and house plants...and much more. Each swap has a different group of vendors.

underwater photography of brown and white fish

Swappy Questions?

Swap Chair: Jeremy Stellhorn

Email: swap@missouriaquariumsociety.com

When is the Next Swap?

Entry is Free!
All Ages Welcome!
Swaps start at 11:00 A.M. and go until 2:00
Refreshments will be sold!

Location

Our Swaps are Held at Jost Chemical!
Located at 8150 Lackland Rd.

Hours

11 AM - 2 PM

Spring Swap - May 9, 2026

Want to Sell?

Tables cost $30 each

If want someome wants a table, they need to reach out to the swap chairman and make their payment so we can get them a table.
Also if they need electricity please let us know as we have limited spots... but they must bring their own extension cords.

Questions?

Monster Fish

The Missouri Aquarium Society (MASI) does not allow the sale (including at swaps, auctions, and on social media) of fish or other animals that grow to an adult size in which they cannot live comfortably in a 200 gallon aquarium, meaning that they are able to access shelter within the tank and can fully turn around within the narrow dimensions of the tank. For most species, this means a maximum adult size of 14 inches. The final decision is up to the MASI Council appointed administrator of the event/platform involved.

Such fish may be offered for free rehoming/rescue.

An exception is made for koi to live in large ponds.

Examples of fish prohibited for sale within MASI include, but are not limited to: Arapaima gigas, redtail catfish (Phractocephalus hemioliopterus), iridescent sharks (Pangasianodon hypophthalmus), silver arowana (Osteoglossum bicirrhosum), pacu (various species including Colossoma macropomum), and tiger shovelnose (Pseudoplatystoma fasciatum). Any fish or other animal banned by Missouri or federal law are not allowed regardless of size.