Here’s the history behind AquaPets:
In 2003, AquaPets were first released in Japan by Sega Toys under the name “Puku-Puku Water Angels”. They were a pretty hot toy, selling 500,000 in the first week of release. The 3 original characters are Puku, Kiko, and Tu. They even did licensed versions like the Postpet mascot and Disney characters (which oddly enough was never released outside of Japan). Outside of the ones mentioned and a promotional Water Angel featuring an air conditioning company's mascot (not even joking...), the line was silently discontinued in Japan shortly after.
You can find others by Googling “ぷくぷくエンジェル”
Their design seems to take inspiration from the Tomy Watergames line. This is a similar concept, only instead the figurine inside is more of a marionette, with movements according to which piece of string is pulled down. *There’s also the fact that you can’t refill an AquaPet, but more on that later.* The actual concept, though, is more like your typical virtual pet, only in a test tube! Each AquaPet has its own unique music and sound.
Sega Toys also made a spinoff called Puku-Puku Resort featuring toy fish that swim around in a tiny dome. Besides the name, it bares little resemblance to AquaPets.
Wild Planet, a US toy company, got the rights to release them outside of Japan. One of the unused names for AquaPets was “AquaAngels,” a reference to the original name. The same trio of AquaPets were released in 2003, featuring the original case designs. Wild Planet then went on to completely redesign them with the the infamous shell shape they’re known for... This design would be used until the line was discontinued around 2007, making way for PursePals. 24 total characters (not including licensed ones) were released in 4 different waves:
There are also some character bios here:
These toys are also notorious for easily forming algae (but this was fixed in the 2010 version):
Fast forward to 2010, and Wild Planet decided to give AquaPets another go. The new design featured a teardrop-shaped case, and all of the characters were redone in different colors. They were discontinued around 2014, leaving 17 characters in total between three different waves. There were also Dew Drops: mini versions that came with a removable figurine and a case that would react to sound. Then, there were Droplets, which included a figurine and case, but no electronic parts.
Now, most AquaPets don’t completely work anymore because the water inside them has been evaporating over the years (yay science). Since Sega Toys and Wild Planet didn’t add a way to open and refill it, many don’t work because they don’t have enough water left for the character to properly float. You could theoretically just drill a hole in it and then refill, but some have said that this can actually damage the toy more. You can still play with the virtual pet portion, but it won’t have the cool animation/puppetry.
Fun fact: Wild Planet also localized Sega Toy’s Handheld Aquarium virtual pet, renaming them as “Aquapalz.”