A good agent can help you negotiate some closing cost credits to help with this , but If you don't have money for close to a 3.5-5% down payment, then I would imagine you'll be in a tough spot if you run into unexpected repairs or vacancy (roof leak, water heater, on and on). 

(either youtube, podcasts on iphone) Listen to it in your car and just have it on 24/7.

I'd tell him I appreciate him as a tenant and Home Depot has a treatment to clean the oil off the driveway and cardboard to put under his leak, and t must get expensive having to put oil i all of the time. 

Tenant called me saying water is leaking from bathroom upstairs to living room downstairs because there was water leakage and accuses me plumbing is old (well, house is only 20 years old).I had multiple problems with this tenant in the past. 

Most insurance claims on houses stem from water leaks.

I had a huge water leak that occurred at one of my rental properties leading to a little of $4000 owed to the water company.

AirBnb has an article on how to use your iphone to get the effects you want. 

Assume 75% of anything water/gas related will be leaking and assume about 5k in electrical work at the minimum 

My concern of course if not the fish, but the tank (not sure of the size) and what happens if it bursts/leaks.

I know the ducts leak attic air into the house so this seemed like a cause.