How can I help my new marine betta

Shnetts · Jul 28, 2025

So I just got a marine betta last week and he doesn’t appear to be doing so hot.

To start I ordered him online and I got an absolute UNIT. He’s about 7in long. Really was not expecting that.

But he’s very very lethargic. Just lays on his side pretty much all day behind the rocks. I planned on having one so I made a pretty large cave on one end of my tank for him but he hasn’t seemed to take to it yet.

He’s not breathing heavy, but is noticeably getting worse each day. I haven’t been able to get him to eat yet. I’ve tried all types of food. Luckily he arrived pretty fat so he’s not malnourished. But the two other fish are completely fine so I really don’t think it’s some untestable water quality issue.

Does anyone have any ideas? Advice?

Baylott224 · Jul 29, 2025

Try to feed it live feeder shrimp or fish. See if it goes for a live prey

bubbgee · Jul 29, 2025

It's nocturnal as far as I remember. Try to feed at night.

vetteguy53081 · Jul 29, 2025

Shnetts said:
So I just got a marine betta last week and he doesn’t appear to be doing so hot.

To start I ordered him online and I got an absolute UNIT. He’s about 7in long. Really was not expecting that.

But he’s very very lethargic. Just lays on his side pretty much all day behind the rocks. I planned on having one so I made a pretty large cave on one end of my tank for him but he hasn’t seemed to take to it yet.

He’s not breathing heavy, but is noticeably getting worse each day. I haven’t been able to get him to eat yet. I’ve tried all types of food. Luckily he arrived pretty fat so he’s not malnourished. But the two other fish are completely fine so I really don’t think it’s some untestable water quality issue.

Does anyone have any ideas? Advice?

They are not nocturnal and do noy worry about feeding it right now. They are knowingly shy and can be this way well over a month.
How did you acclimate fish and for how long?
Keep white lights low the first couple of days and it will slowly grab food while hiding.
Very nice size as mine of 3+ years is maybe 6"

Jay Hemdal · Jul 29, 2025

Shnetts said:
So I just got a marine betta last week and he doesn’t appear to be doing so hot.

To start I ordered him online and I got an absolute UNIT. He’s about 7in long. Really was not expecting that.

But he’s very very lethargic. Just lays on his side pretty much all day behind the rocks. I planned on having one so I made a pretty large cave on one end of my tank for him but he hasn’t seemed to take to it yet.

He’s not breathing heavy, but is noticeably getting worse each day. I haven’t been able to get him to eat yet. I’ve tried all types of food. Luckily he arrived pretty fat so he’s not malnourished. But the two other fish are completely fine so I really don’t think it’s some untestable water quality issue.

Does anyone have any ideas? Advice?

Laying on its side is a bad sign.

How is it "getting worse each day"?

Can you post a video of it?

MnFish1 · Jul 29, 2025

Additionally, did you quarantine the fish. with medications?

Shnetts · Jul 29, 2025

vetteguy53081 said:
Shnetts said:

So I just got a marine betta last week and he doesn’t appear to be doing so hot.

To start I ordered him online and I got an absolute UNIT. He’s about 7in long. Really was not expecting that.

But he’s very very lethargic. Just lays on his side pretty much all day behind the rocks. I planned on having one so I made a pretty large cave on one end of my tank for him but he hasn’t seemed to take to it yet.

He’s not breathing heavy, but is noticeably getting worse each day. I haven’t been able to get him to eat yet. I’ve tried all types of food. Luckily he arrived pretty fat so he’s not malnourished. But the two other fish are completely fine so I really don’t think it’s some untestable water quality issue.

Does anyone have any ideas? Advice?

Click to expand...

They are not nocturnal and do noy worry about feeding it right now. They are knowingly shy and can be this way well over a month.
How did you acclimate fish and for how long?
Keep white lights low the first couple of days and it will slowly grab food while hiding.
Very nice size as mine of 3+ years is maybe 6"

I floated the bag and slowly added water from the tank over 30 mins

Shnetts · Jul 29, 2025

Jay Hemdal said:
Shnetts said:

So I just got a marine betta last week and he doesn’t appear to be doing so hot.

To start I ordered him online and I got an absolute UNIT. He’s about 7in long. Really was not expecting that.

But he’s very very lethargic. Just lays on his side pretty much all day behind the rocks. I planned on having one so I made a pretty large cave on one end of my tank for him but he hasn’t seemed to take to it yet.

He’s not breathing heavy, but is noticeably getting worse each day. I haven’t been able to get him to eat yet. I’ve tried all types of food. Luckily he arrived pretty fat so he’s not malnourished. But the two other fish are completely fine so I really don’t think it’s some untestable water quality issue.

Does anyone have any ideas? Advice?

Click to expand...

Laying on its side is a bad sign.

How is it "getting worse each day"?

Can you post a video of it?

Well it died last night…. It started out almost leading against the rocks. And would move around the tank a few times a day. And by the end of it he was laying almost horizontal and only moved like 6 inches total yesterday

vetteguy53081 · Jul 29, 2025

Shnetts said:
Well it died last night…. It started out almost leading against the rocks. And would move around the tank a few times a day. And by the end of it he was laying almost horizontal and only moved like 6 inches total yesterday

Sorry to hear.
For the future, After floating bag, empty fish and water into a clean bucket and adda cu of water every 10-15 minutes until salinity and even PH is equalized and then introduce fish, preferably into a quarantine tank and allow to settle in and then feed.
With extreme temps throughout the US, it makes matters even more difficult and with acclimation, if not done right, fish in shipped bags produce carbon dioxide and ammonia which lowers the pH of the water in the bag, and in turn makes the ammonia toxic to the fish.
Sometimes, the fish will die right in the bag

Shnetts · Jul 29, 2025

@vetteguy53081 i will definitely do that in the future. Could the shock of shipping or me not acclimating properly be the cause of this? He came in last Wednesday.

MnFish1 · Jul 29, 2025

Shnetts said:
@vetteguy53081 i will definitely do that in the future. Could the shock of shipping or me not acclimating properly be the cause of this? He came in last Wednesday.

It could be - but odd to last this long. Additionally, since you have other fish that you also added (though different fish react to acclimation differently) suggest that acclimation should not be a huge factor. I would strongly consider treating your fish with copper and parzipro if they have not been quarantined - in a separate hospital tank. BTW - the fact that you have other fish that also do not have symptoms mitigates against a disease - but if you decide not to do it I would watch them carefully. Sorry about your betta - I have found them to be beautiful but difficult.

vetteguy53081 · Jul 29, 2025

Shnetts said:
@vetteguy53081 i will definitely do that in the future. Could the shock of shipping or me not acclimating properly be the cause of this? He came in last Wednesday.

Possibly yes. This fish , a member of grouper family will last a little longer in distress.

Shnetts · Jul 29, 2025

@MnFish1 all the fish were quarantined prior to me getting them. So im pretty confident it’s not a parasite or disease. It was also a marine betta or comet fish witch are pretty resilient to disease and to my knowledge and research are pretty hardy

MnFish1 · Jul 29, 2025

~~I believe batfish Marine Bettas and groupers are not related.~~ : EDIT I don't know where I got the idea that you had a Batfish. Which type of marine betta did you receive? Lastly - unless you know exactly how the fish were quarantined, it's impossible to completely trust that the fish was quarantined. And since the fish died - I think disease at least needs to be considered.

Shnetts · Jul 29, 2025

@MnFish1 I’m very confident that it was quarantined the right way. Not saying that disease isn’t a possibility because it always it but it’s all least at the bottom of my concerns. Wdym what type of beta? I’m pretty sure there’s only one kind of

Shnetts · Jul 29, 2025

@vetteguy53081 i forgot to mention it died with his mouth completely open. I’ve seen things in the past where that only happened for certain reasons. Is that anything to look into?

MnFish1 · Jul 29, 2025

Shnetts said:
@vetteguy53081 i forgot to mention it died with his mouth completely open. I’ve seen things in the past where that only happened for certain reasons. Is that anything to look into?

It is usually a symptom of a gill disease or low oxygen/ammonia - but is very non-specific.

MnFish1 · Jul 29, 2025

Shnetts said:
@MnFish1 I’m very confident that it was quarantined the right way. Not saying that disease isn’t a possibility because it always it but it’s all least at the bottom of my concerns. Wdym what type of beta? I’m pretty sure there’s only one kind of

I was just answering your question with my opinion. Normally, acclimation issues do not cause death a week+ later - I think it's important to mention quarantine done outside your own control is always suspect and to carefully monitor your other fish. " There are actually two very similar species, C. altivelis and C. argus, though C. argus is rare. C. altivelis is the more common one found in the aquarium trade. Both species are characterized by their black bodies adorned with white or blue spots, a false eye spot near the tail, and elegant, elongated fin"