Fish died after 1st gravel vacuum - Start over?

Hello all,

Looking for some advice on what to do after the passing of my Betta (Valentine) following a major gravel vacuum. After doing some extensive research, I believe I may have released hydrogen sulfite into the water while performing the 1st (and only) major vacuuming of the gravel to remove this black dirt like substance that had built up and was causing a really bad odor (like rotten eggs).
Also lost 2 nerite snails a few days later so there's something in the water.

The Story (can skip if desired):
What I believe happened,
- I overfed my Betta on the regular and it caused more build up in the gravel
- Had lucky bamboo planted in the gravel (leaves above water) and the roots were always black and smelled when I checked them (replaced a few times)
- Removing the bamboo (thinking the black roots were causing water clarity and smell issues) and heavily vacuumed (for the first time) all of the gravel from corner to corner, stirring up a cloud (possibly a cloud of death)

Betta immediately acted different after the cleaning (didn't eat, swam irraticaly) and died within 48 hours while I was trying to figure out why he seemed sick.

Advice needed:
I ordered a betta that is arriving in 7-10 days and wanted to know if I should clean everything out and start over (using the old filter media), OR just do more gravel vacuum and water changes before he arrives. Also, some of the gravel is still black (ish) from the debris.

Note:
- Currenty perform weekly water changes (25% or so)
- Test water weekly with the current latest
- Amonia 0-.25 (hard to tell with the yellow color)
-Nitrite 0
- Nitrate (between 0-5)
- No fish currently in the aqurium (do have 1 new nerite snail tho)
-Large gravel substrate
- Spiderwood
- Java fern, Java moss, anubias
-No CO2 (liquid dosing)
- Tank was cycled (not sure if it started over now that I still have a bit of a cloud)

Any advice would be greatly appreciated as I'd like and need to have it ready for the new arrival (can't cancel but guess I could keep in my small 1gallon with a heater if needed).

 

So the way I understand it, your tank is currently empty, with no animals in it. I'd just vacuum until it looks decent, but wouldn't be too pedantic about it - a little bit of mulm might be a good thing to keep the beneficial bacteria fed and alive until the new fish arrives. A gravel in a fish tank never looks perfectly clean - that is why I prefer types that are dark in the first place. If you have a light gravel and think you might have made an error and would like to go with a darker one instead - this is your chance to change it.

As I understand it, the hydrogen sulfide is only dangerous when you disturb the gravel - like you did - and not so much if you just leave it be. It gradually dissipates and get oxidized into harmless sulfate (one more reason to have a well oxygenated aquarium). Provided you don't overfeed (I trust you've learned that lesson already), and your tank is planted, there's no need to vacuum deep into the gravel - just go over the surface of open areas and you're done.

 

You say this was your first gravel vac. How long was the tank up and running prior to this?

You say "Large gravel substrate". What diameter are the individual pieces (average) and how deep, in mm or inches?

 

So the way I understand it, your tank is currently empty, with no animals in it. I'd just vacuum until it looks decent, but wouldn't be too pedantic about it - a little bit of mulm might be a good thing to keep the beneficial bacteria fed and alive until the new fish arrives. A gravel in a fish tank never looks perfectly clean - that is why I prefer types that are dark in the first place. If you have a light gravel and think you might have made an error and would like to go with a darker one instead - this is your chance to change it.

As I understand it, the hydrogen sulfide is only dangerous when you disturb the gravel - like you did - and not so much if you just leave it be. It gradually dissipates and get oxidized into harmless sulfate (one more reason to have a well oxygenated aquarium). Provided you don't overfeed (I trust you've learned that lesson already), and your tank is planted, there's no need to vacuum deep into the gravel - just go over the surface of open areas and you're done.

thank you very much for this

You say this was your first gravel vac. How long was the tank up and running prior to this?

You say "Large gravel substrate". What diameter are the individual pieces (average) and how deep, in mm or inches?

Hello, yes I had a bit of a challenge following advice during the new tank setup (believed in order to maintain BB, don't vacuum the substrate and I just never did after the cycle completed).

- Tank has been running approx 4 months total.
- Indivicual pieces vary between about 1/4-1/2 inch.
- It slopes from 2 inches to about 1 1/2 inches

(See current situation pic on left)

Also, after all of that its still recovering from super cloudy water after I "rescaped" to remove (what I thought initiated things) the lucky bamboo.

 

Get rid of the substrate. Or at least, never use it again for aquarium purposes. 9 out of 10 people that seek advice on this forum after experiencing issues, have similar substrates.

The substrate has two disadvantages: it traps waste and the waste is processed slower. The sewer/egg smell seems to indicate this. It is not hydrogen sulfide, but CO2 that has a similar smell when oxygen levels are low. The waste is broken down by microbes, resulting in CO2. The microbes use oxygen. The bad smell indicates low oxygen levels. And low oxygen levels can begat bacterial toxins.

So 1) replace the substrate with any sand with a grain size of 1-3 mm, 2) never clean the substrate; the waste should be processed by the microbe community in your sand substrate, 3) feed less; a betta only needs, let's say 0.1g of food a day, 4) keep a few of those large pebbles as I think it fits your nice little scape , 5) add dry leaves, like oak or the popular catappa leaves; dry leaves are also a "waste" product (which will be processed), but also contains humic substances, which creates a more complex microbe community (complex = stable) and benefits your next betta in a few ways, and 6) make sure the water surface is agitated to increase oxygen levels (not for your betta, but for microbes).

Waste is not bad as long as it can be processed.
A healthy substrate can be stirred; rescaping should not be a problem.

 

Get rid of the substrate. Or at least, never use it again for aquarium purposes. 9 out of 10 people that seek advice on this forum after issues, have similar substrates.

The substrate has two disadvantages: it traps waste and the waste is processed slower. The sewer/egg smell seems to indicate this. It is not hydrogen sulfide, but CO2 that has a similar smell when oxygen levels are low. The waste is broken down by microbes, resulting in CO2. The microbes use oxygen. The bad smell indicates low oxygen levels. And low oxygen levels can begat bacterial toxins.

So 1) replace the substrate with any sand with a grain size of 1-3 mm, 2) never clean the substrate; the waste should be processed by the microbe community in your sand substrate, 3) feed less; a betta only needs, let's say 0.1g of food a day, 4) keep a few of those large pebbles as I think it fits your nice little scape , 5) add dry leaves, like oak or the popular catappa leaves; dry leaves are also a "waste" product, but also contains humic substances, which creates a more complex microbe community (complex = stable) and benefits your next betta in a few ways, and 6) make sure the water surface is agitated to increase oxygen levels (not for your betta, but for microbes).

Waste is not bad as long as it can be processed.
A healthy substrate can be stirred. Rescaping should not be a problem.

thank you very much and that explanation definitely makes sense as I have low flow in the tank (purposely slowed the output to help with the Betta not being blown around) and always had a feeling the O2 levels were low.
Also, perfect timing as I had a plan to rinse the gravel today but instead will move to a sand substrate.
Guessing this is all going to start my cycle over but I'll use the tips and tricks from other posts and keep my existing filter media as is and re-use to help speed things up.
Will update along the way.

 

Not sure about the cycle; replace the substrate and place the decor back; turn filter on once again; perhaps wait a few weeks and you're ready. Especially if your water is soft and ph is low (the water most fish in our hobby, including betta's, require), don't worry too much.

Low filter rate doesn't have to be a problem. What helps is if you could add an air diffuser to the outlet, the "thingy" that causes a few air bubbles; this breaks the water surface most effectively. Continue to run the filter at "low speed" is not a problem.

I would also recommend a few cryptocoryne ....for instance, wendtii or parva species. Bulletproof plants, that initially melt, but comes back strong on its own. It offers various benefits, including for your substrate.

 

Not sure about the cycle; replace the substrate and place the decor back; turn filter on once again; perhaps wait a few weeks and you're ready. Especially if your water is soft and ph is low (the water most fish in our hobby, including betta's, require), don't worry too much.

Low filter rate doesn't have to be a problem. What helps is if you could add an air diffuser to the outlet, the "thingy" that causes a few air bubbles; this breaks the water surface most effectively. Continue to run the filter at "low speed" is not a problem.

I would also recommend a few cryptocoryne ....for instance, wendtii or parva species. Bulletproof plants, that initially melt, but comes back strong on its own. It offers various benefits, including for your substrate to help process carbon and nitrogen compounds.

awesome thank you for that recommendation for the cryptocoryne, will pick that up when I get the substrate later this afternoon

 

I use river stones I'd say around the size you use, and yes, everything that goes to the bottom settles into it and out of sight and the fish can't get to any of it either.
I vacuum regularly though.

the problem isn't the substrate necessarily, the problem is using the wrong strategy on the wrong substrate, the whole "don't clean the substrate" thing is for sandy bottom, everything sits on top and just a bit settles in, as it decays on top it eventually becomes fertilizer and seeps in or winds up drifting to the filter.

with a rock bottom, you kind of have to vacuum to get it out of there or you wind up with a brown cloud that kicks up and kind of sludge down there.
I don't know about hydrogen sulfide, you kind of need an anoxic zone in there for something like that to happen. substrate itself isn't deep enough to do that..... Maybe roots locking up and blocking oxygen to that area? maybe the two inch of gravel and then the statues/ornaments and directly under those areas, an anoxic zone? that happens with reefs or cichlid tanks when the rock work is to big to move and vacuum under or around and the extra blockage of water flow of the rockwork sets the stage as everything collects under it and naturally collects there over time.

yeah, I suppose this is possible to get an anoxic zone and a hydrogen sufite blast when it was finally disturbed, but it's not the rocks or the decoration, it was that it wasn't cleaned out that caused it.


river stones and coarse gravel serve a purpose but it doesn't function the same as sand or soil substrates. it's basically a "curtain" of sorts, to keep the fish away from the waste and poop, and to hide what builds up. It "can" be used for plants, but not really meant to be used for plants, much like how a flowing river doesn't have much plant except along the edges with the least flow, rock like this is kind of just meant for hiding the debris out of reach of the fish and view until you get a vacuum in to remove it. where bare bottom would show literally everything and the fish would have easy access to it.

Only people I know, myself included, that use this type of rock, swore off plants and soils and do a vac out with every water change because we have nowhere for nitrates to go except to sit there and no use for the nutrients from decaying matter either.


I do know if you let stuff build up in this type of substrate, get "crazy" about it, just let it ride!!!!,
and then go in and really kick it up, stirring up all that bacteria that was settled in, the decayers and the nitrifiers, the whole shebang gets disturbed and enters the water column, you will get a significant decrease in dissolved oxygen levels in the surrounding area as all of these bacteria in the substrate come into the water and immediately start consuming oxygen from it where they were happily laying low and consuming the abundance of waste below the rocks, and if or if not fish dying from the lower oxygen levels in the water, a probable spike in ammonia and/or nitrites to follow with this bacterial kickup, and then a rise in nitrates as you've removed the food for all of those once happily feed decay bacteria, they switched to oxygen to try to survive, and depleted that and then there's a die off of them to sustainable amounts.

Just saying it doesn't HAVE to be hydrogen sulfide, it can just as easily be localized oxygen depletion from stirring up all that bacteria and removing what they were feeding on, and if it was the entire tank bottom, localized could be the entire tank.

if keeping plants and enjoying plants, yeah I'd say go for soil/sand substrates, it's just better overall for plants than stones.

 

I use river stones I'd say around the size you use, and yes, everything that goes to the bottom settles into it and out of sight and the fish can't get to any of it either.
I vacuum regularly though.

the problem isn't the substrate necessarily, the problem is using the wrong strategy on the wrong substrate, the whole "don't clean the substrate" thing is for sandy bottom, everything sits on top and just a bit settles in, as it decays on top it eventually becomes fertilizer and seeps in or winds up drifting to the filter.

with a rock bottom, you kind of have to vacuum to get it out of there or you wind up with a brown cloud that kicks up and kind of sludge down there.
I don't know about hydrogen sulfide, you kind of need an anoxic zone in there for something like that to happen. substrate itself isn't deep enough to do that..... Maybe roots locking up and blocking oxygen to that area? maybe the two inch of gravel and then the statues/ornaments and directly under those areas, an anoxic zone? that happens with reefs or cichlid tanks when the rock work is to big to move and vacuum under or around and the extra blockage of water flow of the rockwork sets the stage as everything collects under it and naturally collects there over time.

yeah, I suppose this is possible to get an anoxic zone and a hydrogen sufite blast when it was finally disturbed, but it's not the rocks or the decoration, it was that it wasn't cleaned out that caused it.


river stones and coarse gravel serve a purpose but it doesn't function the same as sand or soil substrates. it's basically a "curtain" of sorts, to keep the fish away from the waste and poop, and to hide what builds up. It "can" be used for plants, but not really meant to be used for plants, much like how a flowing river doesn't have much plant except along the edges with the least flow, rock like this is kind of just meant for hiding the debris out of reach of the fish and view until you get a vacuum in to remove it. where bare bottom would show literally everything and the fish would have easy access to it.

Only people I know, myself included, that use this type of rock, swore off plants and soils and do a vac out with every water change because we have nowhere for nitrates to go except to sit there and no use for the nutrients from decaying matter either.


I do know if you let stuff build up in this type of substrate, get "crazy" about it, just let it ride!!!!,
and then go in and really kick it up, stirring up all that bacteria that was settled in, the decayers and the nitrifiers, the whole shebang gets disturbed and enters the water column, you will get a significant decrease in dissolved oxygen levels in the surrounding area as all of these bacteria in the substrate come into the water and immediately start consuming oxygen from it where they were happily laying low and consuming the abundance of waste below the rocks, and if or if not fish dying from the lower oxygen levels in the water, a probable spike in ammonia and/or nitrites to follow with this bacterial kickup, and then a rise in nitrates as you've removed the food for all of those once happily feed decay bacteria, they switched to oxygen to try to survive, and depleted that and then there's a die off of them to sustainable amounts.

Just saying it doesn't HAVE to be hydrogen sulfide, it can just as easily be localized oxygen depletion from stirring up all that bacteria and removing what they were feeding on, and if it was the entire tank bottom, localized could be the entire tank.

if keeping plants and enjoying plants, yeah I'd say go for soil/sand substrates, it's just better overall for plants than stones.

very insightful thank you Yeah I definitely was not 100% sure it was the sulfide thing but something made things toxic and that was the only chage I did prior to the sad event. But I did learn to take action faster (I knew he was sick and should've moved him while investigating, don't overfeed etc.) if/when I identify a change in behavior for my next fish member.

I may try the river stones again in a future aqurium knowing what I know now.
Again, thank you

 

First, I'm a bit surprised that it got that bad in only 4 months, but you did admit to over feeding and it obviously was trapped in the substrate and built up. Also an abundance of "black" (rotting?) roots that you had to pull out doesn't seem very healthy.

Here's the thing about "bacterial toxins", (mentioned above) or what ever it was that caused the rotten egg smell and "death cloud" that ultimately killed your fish and snails: It could never have happened with regular gravel vacuuming.

These toxins take time to build up to dangerous levels. Regular gravel cleaning ensures this will not happen, so in my estimation it is the safer way to go.

There's plenty of ways to keep healthy fish, and not vacuuming a substrate can certainly be one of them in some instances. Having said that, the incident of death when an undisturbed substrate eventually gets stirred up (like experienced here) is not uncommon.

 

First, I'm a bit surprised that it got that bad in only 4 months, but you did admit to over feeding and it obviously was trapped in the substrate and built up. Also an abundance of "black" (rotting?) roots that you had to pull out doesn't seem very healthy.

Here's the thing about "bacterial toxins", (mentioned above) or what ever it was that caused the rotten egg smell and "death cloud" that ultimately killed your fish and snails: It could never have happened with regular gravel vacuuming.

These toxins take time to build up to dangerous levels. Regular gravel cleaning ensures this will not happen, so in my estimation it is the safer way to go.

There's plenty of ways to keep healthy fish, and not vacuuming a substrate can certainly be one in some instances. Having said that, the incident of death when an undisturbed substrate eventually gets stirred up (like you experienced here) is not uncommon.

you'd be surprised what my overfeeding family member can do to a tank just handling 1 feeding a day in just a weeks time. she's got flake food tumbleweeds rolling across the bare bottom of the tank, it makes me crazy how much goes to waste that those fish can't possibly eat. I might take a picture when I get home of it, it was vac'd and water changed on saturday night you should see it now!
*edited* to add a picture of this atrocity after barely 4 days.


I just clean it nowadays. it's an argument I can't win and it won't change. The fish don't eat when they are spawning, and she'll go and put food in every hour because "they don't eat for days they must be hungry!"

Noooooo.... Because I fatten them up when they ARE eating to compensate for when they dont.... If I get on about this though, she'll nitpick about a hundred other things I do to get revenge so I learned to shut up and just do the extra water changes.
Anyways imagine all that junk sitting under rocks for 4 months, that's just 4 days. I bet DovC does overfeed as he admitted to, but I bet it was nowhere as bad as this! Hahaaha!

 

wow thanks for this. I feel slighly less bad about my overfeeding which I won't allow myself to do again in life (for the fish that is not me. lol)