How to block off holes

[LeePakao]

Hi, in my 75 gallon tank i have a lot of hiding spots and random places to hide for my fire eel, red tail black shark, and black ghost knife. But because my fire eel has grown a lot since first getting him he's beginning to get to big for some of the stuff in my tank. Unfortunatly, alot of the things he is getting stuck into only has one small hole and the rest big holes so i dont wanna get rid of them. As for now though they are removed.

I was wondering if there was something i could use to "fill" the holes or have them blocked off by something. I was thinking of using a corc from a wine bottle but have heard alcohol can kill your fish quite easily. Any suggestion would mean alot Ive tryed using shells but the eel is quite strong and moves them out of his way.

P.s i cnt use rocks because i use sand in my tank and the mixture of the two creates a chemical under water that will harm(possibly kill) the fish/eel.

Thank you for all your suggestions!

 

[Egon]

I was thinking of using a corc from a wine bottle but have heard alcohol can kill your fish quite easily.

P.s i cnt use rocks because i use sand in my tank and the mixture of the two creates a chemical under water that will harm(possibly kill) the fish/eel.

Thank you for all your suggestions!

1) So alcohol from the cork can kill your fish? Does that make sense? Math wise your talking a very small amount of alcohol to a large amount of water if the cork is still wet, like you just opened your bottle of wine. I don’t think the cork will hurt your fish. How about this: I will put just a drop of wine in my tank and let you know if it’s safe……….that’s like a thousand times more wine than what’s left on the cork.
2) I have been using sand and rocks in my fish tanks for years, never had a problem. Do weekly 10% water changes and gravel vac the sand once in a while. Don’t over feed the fish and you won’t have any chemical issues ever.

 

[peacock madness]

i dont understand how the combination of ur sand substrate and rocks will make a chemical reaction??? explain why u gtn thonk this so maybe we can understand ur reasoning btr to help more

 

[boldtogether]

P.s i cnt use rocks because i use sand in my tank and the mixture of the two creates a chemical under water that will harm(possibly kill) the fish/eel.

What?
If you are talking about rocks possibly raising or lowering the PH, then ok, but rocks and sand dont make a toxic combination unless the sand and rocks each are toxic.....never heard this one. The only time you would need to be concerned about rocks and sand being chemically incompatible would be if your fish cant tolerate silica, high PH..etc.
Eels, wont go in where they cant get out generally speaking, but if you have an aversion to rocks and other natural decor, try experimenting with regular household items like flower pots, PVC pipes, glass tubes from oil lamps(new)etc..

BTW, alcohol in the cork would be long ago evaporated...

 

[Egon]

I think the OP is talking about pockets of ammonia getting stuck under the rocks maybe? So there's a build up of anirobic bacteria because the rock is making pockets in the sand for this stuff to build up. A lot of people think sand is bad for aquariums for this reason.