Goby guts?

[KeyWestSeasalt]

Ok gang, I have a question for you experts. I have 3 engineer gobies in my tank. They are awesome and are, as far as we can tell, loving life in there. I believe one of them is a female as she has a bigger abdomen than the other two and is slightly larger. We've had them for a little over a month and it's cool watching them change the landscape all the time.

This morning, my wife was watching them and the "female" swam up towards the surface and something alien popped out of her and floated to the surface. It looks like some kind of egg sac or something, but I can't find anything that tells what it is. Unless she's crapping her intestines out, I'm confused as to what it is.

We've been seeing this reddish stuff in the tank by the filter for the last few days and assumed it was something coming off of the live rock. I'm attaching a picture of it if anyone can give me some insight.

 

[54seaweed]

Nothing to worry about my engineer does that too , first time I saw it I was freaked out too , it's a webbing they spin to prevent predators from eating them while sleeping , it's almost like a spiders silk , I never seen a reddish color though , I always see white ones or grayish ones , first time I saw it I had no idea what it was looked like a alien pod

 

[Reefing Madness]

The Engineer Goby will surround itself in a mucous cocoon that they produce from their own body, they do this when sand is not present in the aquarium, or when not enough sand in the aquarium is present. Gobies survive best with deep sand beds, that they use to make home

Deep sand beds are what they use to escape predation in nature. Therefore if your aquarium is lacking sand, Goby will produce this mucus cacoon around itself every night, which helps with not only a sort of camouflage, but it hides the scent of the fish, by keeping predator fish from finding it and eating it. This is how these rather smaller species of fish have survived for thousands of years in nature, by using survival techniques like this.

My suggestion would be to add more sand to your tank for the Goby to burrow in.