Inkfish

The Inkfish is a small aquatic fish. They grow to be roughly 5cm long and are very thin. They look to be black with stripes, but their skin doesn't hold any pigment. Instead, the pattern comes from its blood vessels shining through and its black blood. This odd color for blood is what makes the Inkfish so valuable and its easy upkeep makes it one of the few legal animals to keep and breed by breeders in the fallen city. When the Inkfish reaches the end of its lifespan it is taken and with a small incision right by its major artery, the blood is taken out. This blood is then used as ink when writing letters. Due to how many fish are needed to make the ink, it is fairly costly to produce, but compared to coal or other forms of writing ink from the Inkfish is the only one who can withstand longer transport by a carrier lizard without being smudged. With the amount of correspondence being sent between the city, its districts, and all the people within them the ink from Inkfish is highly desirable and valuable. The Inkfish is fairly easy to take care of. Living naturally in big schools of fish you can keep a lot of them in the same tank without much issue, and being used to living in lakes with harsh winters and warm summers the temperature of the water can fluctuate quite a bit before they take notice. The Inkfish live off of algae and other plant life in the water, so rocks full of algae is usually placed at the bottom of the tank underneath a net, letting the algae come out into the water without the Inkfish eating it all up without a chance for the algae to reproduce and grow.