Yesterday (Tuesday, 7 April 2026) was a big day for the pond. After noticing the water level falling, I purchased a Boogie Blue Plus Garden House Filter (that’s an Amazon Affiliate link; I receive a portion of any purchases made through this link, at no additional cost to you) and topped off the pond.

I also had a shipment of Japanese Trapdoor Snails from www.prettykoifish.com.  I have been dying to add these massive mollusk beauties to our pond since I first learned about them.  They are the cleaning crew of any pond, and as they settle in and become active, they’ll deep clean the water and the liner.

Right now, our pond water is very murky.  That’s actually good for the koi—they prefer it to be murky—and is a sign of healthy biodiversity.  The only downside is that we can’t see our fish unless they’re coming up to feed!  It will take a few weeks, maybe months, but the Japanese Trapdoor Snails should start to hoover up lots of detritus.

There is a tree—a Japanese elm or maple—next to the pond, and it is shedding quite a bit of plant matter each day as it is leafing.  That ends up in the filter.  The koi eat some of it, but usually by mistake while eating their real food.  I had such a biomass accumulate Sunday evening that on Monday morning there was a rank smell coming from the filter, along with gnats flitting about.

My fear was that two new butterfly koi I’d introduced had gone the way of Milkshake and Brownie, the juvenile koi we introduced to the pond in January.  Fortunately, I have not found either of them gathering pond scum in the filter.  Instead, the stench was just coming from the sheer accumulation of detritus—in one night!

Too much of that for too long can hurt the quality of the water, and while koi are fairly hardy, they have their sensitivities to water quality like all fish.  I don’t want our koi merely to eke out a miserable existence while we gawk at their colors; I want them to thrive!

That goal dovetails with our desire for better visibility. The Japanese Trapdoor Snails will slowly clean up the gunk and muck and scum in the pond, and the water clarity and quality will improve.

According to my research (which is mostly talking to CoPilot), ten Japanese Trapdoor Snails is typical for a pond our size.  However, I dropped fifty-eight-ish into our pond (we ordered fifty-five, but they sent three extra in case any snails were D.O.A.; from what I can tell, I think only one had perished, and that’s based on a single empty shell).  That’s not an overdose, though; it’s an intentional gut-punch to the pond’s gunk problem.

For giggles, I asked CoPilot what would happen if I dropped 1000 JTSs into the pond (I’m not going to do that).  Essentially, it said that the fish would be fine, but that the snails would eat every bit of uneaten food and gunk and biomass in mere days and be wondering where all the food went.  That tells me that 55-58 snails aren’t going to hurt anything.

The snails themselves are impressive specimens:

As they get accustomed to their new home—which will take between 24-48 hours—they will start to show up near the surface in the evenings (allegedly), although I don’t expect I’ll see much of them.  I did place ten directly into the filter, beneath the filter basket, so I imagine if I’m going to get regular sightings, it will be in there.  Those lucky ten—the aristocratic elites of the pond snails—will get the most food, as everything in the pond slowly makes it way to that filter.  It should also cut down on how often I need to empty the filter basket.

The rest of the snails were plopped and dropped all throughout the pond.  Here’s one I put on a shelf in the liner for a quick photo op before relocating him deeper into the waters:

In addition to adding the newest denizens to the pond, I topped off the water levels.  I made a lengthy video about it (in which I ramble and discurse even more flagrantly than I do on this blog), in which I detail the process of filling up a pond safely:

Chlorine is a death sentence for fish, so a proper dechlorinator is a must.  I was thrilled to find the hose attachment variety, as I was dreading filling up buckets of water with liquid dechlorinator mixed in, and then adding one bucket at a time.

Instead, I slowly filled the pond over the course of about two hours.  I took care of laundry and some dishes while it filled, and the Japanese Trapdoor Snails arrived around the time it finished.  I fed the koi during and filling to make sure they were taking to the water nicely, and they came right up to feed.

It helped that yesterday was a bit colder, so there wasn’t a quick shock to the temperature as I added the cooler, dechlorinated tap water to the pond.  I imagine the cooler weather will also help the snails acclimate.

As for the ramshorn snails I added earlier in the year, they were quite young, and I don’t know about their fate.  I imagine the koi picked off some of them, but I hope the others survived and are burrowed into the soil at the bottom of the pond.  They will complement the JTSs nicely, as the two don’t compete and, as snails, they’re not aggressive.

Finally, I did a little research into other species that I could introduce to the pond to improve the biodiversity while also protecting the existing population.  I also don’t want to overload the pond with too many species.  CoPilot mentioned that I can safely introduce green and leopard frog tadpoles (but never bullfrog tadpoles, as they take forever to mature; make a huge mess in the process; and grow into bullfrogs, which will eat anything in their path and are hugely aggressive), as well various local species of minnows.

To that end, I obtained a $10, one-year, freshwater fishing license from the South Carolina Department of Natural Resources.  That license allows me to collect small numbers of tadpoles and non-endangered minnows legally.  I’d like to introduce some Golden Shiners to the pond, which are apparently sold in many bait shops already.

I also want to add three (3) weather/dojo loaches.  These odd, elongated fish are peaceful bottom feeders that love to live in groups of three.  They don’t compete with koi and don’t bully smaller fish.  Instead, they eat algae and leftover food that drifts to the bottom of the pond.  They’re also cold-hardy, so they won’t die off in the winter like tropical loach species.

So—big plans ahead!  I’m looking into getting a net and a minnow carrier for hunting down frog eggs and minnows.  CoPilot put together a nifty little guide for me on how to identify the different minnow and frog species so I get animals that are safe and legal.

Of course, I had this composition in my head while dropping in the snails:

More to come!  Now that Spring is here, there’s a lot of excitement about the pond.  We think we have around ten koi in total, although it’s hard to count them.  The increased clarity that we should experience in the months ahead will really help identify the koi and any surviving rosy red minnows, ramshorns, butterfly koi, and JTSs.

What would you put in your backyard pond?  Are there any floating plants I should try?  Let me know!