Calculating haidh for a woman who has never experienced a minimum of 15 complete days of tuhr

Q: I am confused regarding my haidh. Please advise.

I get haidh consisting of red blood for around 7-8 days each month. The rest of the month I get a discharge (varying between clear, white and yellow, most of the time it is yellow).

I used to consider my haidh as 10 days (the 7 or 8 days of blood and 2 or 3 days of discharge). Then I would make a ghusl and make wudhu for every salaah thereafter until I see blood again.

I do not get my haidh on the same days of the month (i.e. a few days before or after the last date). For the past 5 years, my haidh has been like this. I used to get my haidh for two years prior to these 5 years, but unfortunately I did not record my cycle (I think it was the same like the 5 years).

Below is the days I've recorded as haidh for the past year in the manner as stated above:

2019 
- 8 Oct - 18 Oct
- 11 Nov - 21 Nov
- 17 Dec - 27 Dec

2020

- 17 Jan - 27 Jan
- 11 Feb - 21 Feb
- 21 Mar - 31 Mar
-27 Apr - 6 May
- 31 May- 10 Jun
- 1 Jul - 11 Jul
- 31 Jul - 10 Aug

Please advise.

Zakaat on a fish farm

Q:

1. I have a fish farm. How do I pay zakaat on it ? Do I have to pay zakaat on the amount of fish I have purchased for or do I have to pay on the current market price of all the fish I have?

2. What if most of the fish died and I am unable to know the exact amount of fish in the farm?