Now fish is something else.. they harm the fish in the process of dyeing them. It's painful for them. For some they have to literally strip the slime coat off the fish using chemicals. Leaving the fish injured and unprotected. Some are dipped in dye that burns into their unprotected body, some are injected with dyes, like glass fish, some are even tattooed to be more colorful. I wouldn't tattoo my 10 year old, so no, I wouldn't tattoo a fish..
But dog dyes are designed not to harm the dog if ingested. They're mostly plant based. There are no injections and no bleaching, it's not painful any more then giving a dog a good bath is. Unless Mr Bubbles is a black dog and they've bleached him, which can be painful (so says my daughter.. steam is hot!) and the chemicals can hurt the skin... no, I see no cruelty in dyeing a dog. Besides, most dogs LOVE attention.. I bet Mr Bubbles gets tons of it when he's out like that!