Cleaning a neglected tank?

My brother has a 29g that he got 2-3 years ago, and after putting some fish in it he lost interest. He does water changes only when our parents force him to. He recently gave me three of his surviving fish to rehome in my tanks, but there are still two other fish in his tank that I can’t do that for.
I’ve heard that it’s best to clean a tank in this kind of condition gradually to avoid shocking the fish. How should we go about that?

 

Start with regular water changes. I'd go easy on it first, say 25% for the first few times with light gravel vacuuming, then bump it up to 50%. After a few weeks of good water changes I'd do a good cleaning of the glass and filter media.

 

A photo would help. I've gotten a few neglected/ re-homed tanks here and there and I normally totally re-do them and just do a fish-in cycle again. The ones I've gotten were beyond fixing which is why, but i have no idea the state of the one you have, maybe regular maintenance will be enough.

 

My brother has a 29g that he got 2-3 years ago, and after putting some fish in it he lost interest. He does water changes only when our parents force him to. He recently gave me three of his surviving fish to rehome in my tanks, but there are still two other fish in his tank that I can’t do that for.
I’ve heard that it’s best to clean a tank in this kind of condition gradually to avoid shocking the fish. How should we go about that?

Since the fish very gradually got used to the bad conditions it is best to make changes gradually. If I found myself in this situation I would do daily water changes starting with 10% the first day, 15% the next, 20% the next. Continue doing this until you are up to 50%. By then the fish and cycle should be able to handle a bit of tank cleaning like vacuuming the gravel. Slow and steady should get this tank in good shape and the fish shouldn't be overly stressed from the changes.

 

A photo would help. I've gotten a few neglected/ re-homed tanks here and there and I normally totally re-do them and just do a fish-in cycle again. The ones I've gotten were beyond fixing which is why, but i have no idea the state of the one you have, maybe regular maintenance will be enough.

Here’s the tank:

The remaining fish are BN plecos, so at least there’s no algae problem.
It probably just needs water changes and a filter cleaning.... (I hope, anyway.)

 

Here’s the tank:View attachment 712741
The remaining fish are BN plecos, so at least there’s no algae problem.
It probably just needs water changes and a filter cleaning.... (I hope, anyway.)

Oh definitely not bad. Most of the ones I’ve had have been crushed in algae and had like dead snails and plants In them. I would agree with what was said above and just do water changes slowly to get the parameters in check, getting it cycled. Adding driftwood will be great for the pleco, as well as feeding veggies. Other then that, it’s not in terrible shape.

 

What are the water parameters? Did you test it?