Why has my Plec died?

* warning contains a photo of a dead fish!

Sorry for the long post:
I had a Betta in my community aquarium but a lot of people recommended they should live in a aquarium of their own, so I set up a small aquarium to move him into.
I filled the small aquarium with water out of my mature community aquarium.
I also added Seachem Stability (says if used daily for 7 days that fish can go straight in)
and I added Special blend (basically a Biological ecosystem in a bottle) to aid the filter etc.
Between using mature water, the Stability and the Special blend, I thought the aquarium would be fine.
I added my Betta and my Bulldog plec into the small aquarium. They seemed fine, both active etc.
Within a few hours the Plec died, his underside had turned black (I don't know what this would mean).
In a panic - as I didn't want to risk losing the Betta too, I took my Betta out and put him back into the community aquarium.
I tested the water in the small aquarium but the only reading that was different was the PH - which had raised from approx 6.8 up to 7.6
I had the Plec for 11 months and he didn't seem to reach full size (could there have been something wrong with him eg genetically?) so could this, coupled with the stress of moving between the 2 aquariums have killed him?
or would it have been the PH that killed him?
Betta is fine, he's still active and doesn't seem affected.
I would like to try find out the reason for my Plec dying so that I know whether it will be safe for my Betta or if I need to do something first etc.

Photo of my Bulldog Plec's underside when he died:

The bulldog pleco needs really oxygenated water & stable conditions. Did you have an air pump in the new tank? It's not recommended to add to a new tank. The old tank water in new tank doesn't give you the bacteria you need as that comes from bacteria on substrate, filter sponge, decor. Did you test the ammonia & nitrite levels of the new tank before adding fish and again after Pleco died?

I'm really sorry your Pleco died

If you want another Pleco it's best to keep it in the community tank & not with the betta. The bulldog pleco needs tank size of 120cm length x 30cm width but a Bristlenose Pleco is ok in smaller tank size of 60cm length x 30cm width.

Bulldog pleco:

Bristlenose Pleco:

AilyNC said:

The bulldog pleco needs really oxygenated water & stable conditions. Did you have an air pump in the new tank? It's not recommended to add to a new tank. The old tank water in new tank doesn't give you the bacteria you need as that comes from bacteria on substrate, filter sponge, decor. Did you test the ammonia & nitrite levels of the new tank before adding fish and again after Pleco died?

I'm really sorry your Pleco died

If you want another Pleco it's best to keep it in the community tank & not with the betta. The bulldog pleco needs tank size of 120cm length x 30cm width but a Bristlenose Pleco is ok in smaller tank size of 60cm length x 30cm width.

Bulldog pleco:

Chaetostoma formosae – Striped Bulldog Pleco, L444, L187b — Seriously Fish

www.seriouslyfish.com

Bristlenose Pleco:

Ancistrus sp. ‘3’ – Common Bristlenose Catfish, Antennenwels (DE) (Ancistrus sp. 3) — Seriously Fish

www.seriouslyfish.com

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Thanks for your reply:
As well as the water from my mature aquarium, I'd also added stability and special blend. The instructions said it was so fish can be added straight away.
There was a filter, heater and light - just the same as the mature aquarium he'd been in.
Unfortunately I didn't test the water before adding into the small aquarium as I expected it to be the same as the mature aquarium as that was where the water had come from. I did test quickly after he died though. The PH had raised but all other readings were the same as my mature aquarium.
The Bulldog plec only reached 3" despite being in a 180L (UK) aquarium which made me think they could have been something wrong with him and that maybe the stress pushed him over the edge?

On the link you sent me I just saw this. I did say he didn't grow very much etc:

Agree with AilyCN. Chaetostoma formosae is a really sensitive fish that requires very specific conditions. They live in rivers in the uplands of the Amazon, which are cool and fast flowing. That means your tank needs very clean, highly-oxygenated water, like AilyNC said, and there should be current. When I got one, I rearranged the tank so it lived with fish which could cope with those conditions (23C and a big powerhead), and I moved the ones which couldn't to a different tank.

Bettas require minimal flow and warm water, so they're not very compatible species.

I've also found C. formosae grow quite slowly, and they only reach about 4" anyway. If your fish wasn't kept in ideal conditions in your 180L tank, it might have been weakened. And even if you had it in the correct conditions, the PH jump and in the small tank might have done it in anyway. Hypersensitive fish like a lot of the L-numbered plecs don't cope well with substantial PH fluctuations or even tiny amounts of ammonia/nitrite.

Gypsum said:

Agree with AilyCN. Chaetostoma formosae is a really sensitive fish that requires very specific conditions. They live in rivers in the uplands of the Amazon, which are cool and fast flowing. That means your tank needs very clean, highly-oxygenated water, like AilyNC said, and there should be current. When I got one, I rearranged the tank so it lived with fish which could cope with those conditions (23C and a big powerhead), and I moved the ones which couldn't to a different tank.

Bettas require minimal flow and warm water, so they're not very compatible species.

I've also found C. formosae grow quite slowly, and they only reach about 4" anyway. If your fish wasn't kept in ideal conditions in your 180L tank, it might have been weakened. And even if you had it in the correct conditions, the PH jump and in the small tank might have done it in anyway. Hypersensitive fish like a lot of the L-numbered plecs don't cope well with substantial PH fluctuations or even tiny amounts of ammonia/nitrite.

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Thanks for your reply.
I'd had him 11 months and he had hardly grown in that time. I was told they reach 6" bit he only reached 3". He was always active and seemed to feed well etc. Both aquariums had the same conditions and water test results except the PH.
So do you think it sounds as if he was probably weakened then the change in PH and stress of moving etc finished him off?

Would I be better to get a Bristlenose plec for my mature community aquarium? Are they hardier?

Yeah, you were told incorrect info. From a fish shop? Would not be the first time. Those don't reach 6". https://www.planetcatfish.com/common/species.php?species_id=318.

If it wasn't living in the conditions I've described in my first post, then it probably wasn't 100% healthy, and as you say, the PH jump and move finished it off.

Bristlenoses are a lot hardier. They're widespread throughout South America -- which means they haven't evolved to be adapted to the conditions of one river system like a lot of loricariidae -- so they're more tolerant of a range of conditions. Like all fish, they need clean water but you don't have to start blasting your tank with powerheads to keep them. They're a good starter pleco if you're interested in keeping loricariidae.

Fish shops give rubbish advice 99.9% of the time. When I'm interested in getting a new fish, I Google it and mainly look for information on SeriouslyFish, or if it's a catfish, PlanetCatfish.

Gypsum said:

Yeah, you were told incorrect info. From a fish shop? Would not be the first time. Those don't reach 6". https://www.planetcatfish.com/common/species.php?species_id=318.

If it wasn't living in the conditions I've described in my first post, then it probably wasn't 100% healthy, and as you say, the PH jump and move finished it off.

Bristlenoses are a lot hardier. They're widespread throughout South America -- which means they haven't evolved to be adapted to the conditions of one river system like a lot of loricariidae -- so they're more tolerant of a range of conditions. Like all fish, they need clean water but you don't have to start blasting your tank with powerheads to keep them. They're a good starter pleco if you're interested in keeping loricariidae.

Fish shops give rubbish advice 99.9% of the time. When I'm interested in getting a new fish, I Google it and mainly look for information on SeriouslyFish, or if it's a catfish, PlanetCatfish.

Click to expand...

Thank you for the advice. It's a shame that fish shops aren't always helpful as it causes heartache - incompatible fish, wrong conditions etc.
I will check out those pages you recommended

I would get a Bristlenose Pleco for community tank. They're a very fun fish. I'm planning on getting an Albino one for my newish tank.

Just wondering - can you test Nitrite, Nitrate and Ammonia? In particular the ammonia in new tank can cause issues. Even though your tank had mature water & bacteria colony from bottle - these won't mean it's correctly cycled.