Fill the mote with blood instead. Or badgers. The latter even tends to get your more of the former.
This!
Sadly, blood isn't an actual liquid right now. The most you can do is cover the sides and bottom with it.
Yeah, but once you get the moat filled, you could at least get the water bloody, which would be pretty sweet. I do hope that blood gets made useful soon, however, so that I can finally put my blood stockpiles to use (I make a point of always buying all blood barrels from caravans...if just feels right).
Also, if you're in a biome that freezes in winter, that can help a LOT in filling a moat, if you're patient enough to wait several years to get it done:
1) When water of any depth freezes, it becomes a solid ice wall.
2) When said wall thaws, it will be 7/7, regardless of it's pre-freeze depth.
3) If you have a small pond, and drain it into a section of moat in fall, hopefully the whole bottom of the segment will be filled with 1/7 or 2/7 water when winter hits and BAM, instant fill when it all ments and re-thaws.
4) the following fall, do the same with a larger segment (now that you have more water), and after a few years, you can literally multiply a single square of 7/7 water into a completely filled moat.
Conversely, if you have an indoor water source, you can have dwarves fill the moat during the freeze season - as soon as they dump the bucket into the fill zone, it'll freeze. With careful management of the pond zones and whatnot, you could fill the entire moat with ICE, which will then unfreeze into a glorious 7/7 moat in spring.
Of course, if you're in a biome that freezes, a water moat will be completely useless during the winder months, so I suppose this is just mental masturbation, but still...it's a dwarfy way to do things.