Various masaail of Business and Dealings

Trading one tuna for two salmons

Q: I have been curious for a while now about, "what is considered the same جنس when it comes to fish"... more specifically, can I trade 1 tuna for 2 salmons, would it be riba? Is the جنس the entire species of fish (which would entail riba) or is it in each respective sub-species, e.g. tune, salmon, yellowtail etc.?

Receiving extra money from the company one worked for

Q: This incident happened 10 years back.

I worked for an American company in UAE. While travelling in UAE, I billed the company for my travel expenses (as per the company policy) the bill was for 20,000 Dirhams but they transferred USD 20,000 in my account. I contacted the finance person and asked him to send the correct amount and withdraw the wrong amount. He did that, however, few days later, another USD 20,000 was deposited in my account. I contacted the bank this time but they told me it’s the correct amount as per the transfer. So I didn't do anything for 5 years. Few years back (feeling uneasy) I contacted the company again to see if they wanted their money back but I didn’t get a response. What should I do since I have already used this money? I have been giving out sadaqah with the intention of paying back this amount. Is this correct?

Using work facilities for one's personal work

Q: I have made my bio-data, salary voucher, experience letter, etc., in my previous office without taking permission from my boss. I have used the office printer, computer, internet, paper and other things for printing these documents. While doing this, I was aware that it might be haraam.

Can I use these documents for any interviews, jobs or even any other work in future? If I do so, will my job and the income from this job be halaal or haraam? What should I do? 

Supplier storing goods in a liquor store

Q: We have a business and one of our products is bottled water. We were using a supplier to bottle water for us, who was renting a plot from someone else. The owner of the plot passed away. So now our supplier has chosen to move his operation into his other business which is a bottle store... we not sure if we should continue or find someone else? He has moved it to a cold room in the liquor store with only water in the room and no liquor... He still invoices us from his other company as was previously done.

Paper currency

Q: I am reading about the Quran and old Islamic economic system. Is it true that if any country or bank prints paper currency more than gold or silver reserves, it will be ribah or sin? Some Islamic teachers say that paper currency is a fraud because paper currency is more than Gold reserves, and in Islam money is which has intrinsic value like wheat, barley, dates, salt or gold and silver?