You wouldn't ever be able to tell this, because carp fish do not get pregnant. Pregnancy implies carrying the young internally, which carp do not do.
Koi are a type of specially bred carp.
Danios are egg layers and can not get pregnant.
I would imagine that with some fish it would be nearly impossible to tell until they give birth. However, with a thin, transparent fish, you sometimes can see a dark spot in their belly!
it would not be happy if it does not eat that is normal it will loook desperate that's normal too
a catfish has whiskers and a carp doesn't.
To talk; to speak; to prattle., To find fault; to cavil; to censure words or actions without reason or ill-naturedly; -- usually followed by at., To say; to tell., To find fault with; to censure., of Carp, A fresh-water herbivorous fish (Cyprinus carpio.). Several other species of Cyprinus, Catla, and Carassius are called carp. See Cruclan carp.
Goldfish of any type are all egg laying fish which means that they do not get pregnant
With a guppy you need to look at the gravid spot. This is a dark spot in the fish's belly. A large gravid spot indicates the fish is likely to be pregnant. You can tell how pregnant the fish is by how large the spot is. Sorry I have no experience with other species.
Orandas, or any other type of goldfish are egg laying fish, so they do not get pregnant
Your Oscar can not get pregnant. It is an egg layer. It will not be adult or mature until it is around 6 inches long.
Black moors are a variety of goldfish which are egg layers so they can't get pregnant.
A graviid spot is a dark grey spot at the back of the stomach. It is a sign to tell you that your fish is pregnant