You can find the gender of a guppy by looking at the anal fin. The anal fin is the closest fin to their tail below them. On a female it will look like a normal fin but on the male their will be 2 long skinny fins. The male is also much more colorful.
Just in front of her anal fin.
Yes, make sure the water is changed regularly. The tail will grow back but will never be as good as the original one. There will be a reason the guppy has been loosing its tail. If the problem is fungus then you need to fix the bad water problem that is causing the fungus by changing the water regularly. If the problem is fin nipping by other occupants then you will need to separate the fin nipper(s).
The gravid spot can be seen from both sides of a female guppy, but it is located directly in front of the anal fin on the bottom of their abdomen.
The female gets a deeper tummy and there is a dark (gravid) spot by her anal fin.
Would you be sick if bits of you started falling off? Think about it!
You can tell by it's anal fin that is located at the bottom of the fish. If it is a male guppy it will have a gonopodium it looks like a backwards point, and if it is a female it will have a anal fin that looks like a backwards Chinese or Japanese fan. I really hope this helps if not post a photo ok
If the one chasing has a pointed fin underneath his belly, it's a male. If the fin is rounded, it's a female. If it's male and female they are probably mating/breeding.
If your goldfish has red patches, is losing its tail and has a fin clamped shut, this could mean that it is sick. You should take it to a vet if possible.
Every part of the male Guppy helps him to attract a potential partner who will let him impregnate her. From his size, to his colouring, to his fins it all counts. However the actual bit that transfers his milt (sperm) into her is called a "gonopodium". It is a modified anal fin situated on the underside of the fish between the ventral fins and the caudal (tail) fin
Females are larger (around 2 inches) and basically grey in colour and their anal fin is triangular. Males are smaller (around 1.5 inches) have many colours, and their anal fin is pointed.
This is with every fish, the males bottom fin is like a spike as the females are like a circle.