Why do fish randomly die 3 months into my ownership?

[djryan2000]

I've been in the hobby for almost 2 years now. I have a JBJ45 with a mixture of SPS, LPS, softies, BTAs, and rock flower nems. None of them ever give me inexplicable issues - the only time I've seen a decline in coral health my test kits were able to tell me why. Fish, on the other hand, not too much. It's a common occurrence. I buy a fish, quarantine it for 6-8 weeks, put it in my tank, and 2 months later it either goes missing or I find it caught in the flow, dead.
Current fish are a single clown I bought in September of 2019, a wrasse I got last June, a mandarin dragonet I got on 12/1, and a Banghaii Cardinal I bought in October. Some of my fish history is as follows:
- purchased 2 Chromis, 2 cardinals, and a coral beauty in October. quarantine all 5 together for 6 weeks. Put them in DT. 4 weeks in 1 Chromis dies, and then the other a week later. A month ago the coral beauty died.
- I have purchased 4 other clowns to pair with mine. They all last 4-8 weeks and then die inexplicably.
- ORA Komohara blenny is missing today. I added him 2 months ago and he is MIA today
When I purchase fish they go in a QT tank of matching salinity. I let evaporation raise the salinity until it matches my DT tank and then once they're ready they go into the DT.
I believe I am missing a few fish that died in my tank. Each time everything seems good, they are eating, fat, no bullying, and then I check the tank and I'm down somebody, despite the fact they seemed to be in perfect health the day before.

I am honestly at a loss as to why this keeps happening. The corals and nems never show any signs of stress. I don't know what to do besides stop buying fish... any ideas as to what is wrong here?

I am honestly at a loss as to why this keeps happening. The corals and nems never show any signs of stress. I don't know what to do besides stop buying fish... any ideas as to what is wrong here?

 

[gallivanmk]

Are you always buying fish and adding them in groups like that? Adding 5 fish to your tank at once would be a pretty significant bioload increase for a tank that size. What do you have for biological filtration? What type of clown do you currently have and what type of wrasse?

 

[Houdi]

Are you always buying fish and adding them in groups like that? Adding 5 fish to your tank at once would be a pretty significant bioload increase for a tank that size. What do you have for biological filtration? What type of clown do you currently have and what type of wrasse?

I had a clown that I didn't know was attacking my fish until I caught him with a fish in his mouth. Are you always buying from the same vendor? Do you match his numbers when you add these fish?


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[EMeyer]

When fish die but inverts and corals survive its almost always disease. It sounds like you have a disease in your tank, and the new fish are catching it.

 

[Timfish]

In addition to the above comments I had a couplen interesting experineces that might help. One, I got 10 naso tangs in one shipment from my supplier, QTed them then distributed them to 9 clients systems, between 5 and 6 months 9 of them died while there wer no other apparent problems with the other fish. They were eating and had good body weight and didn't ahve any spots or blemishes. Also keep in mind for the most part we can't tell how old a fish is. Some actually have very short life expectancies and a common charicteristic of older fish will be reduced ability to deal with stress. There's problems fish can have and there's no way we can discern just by looking at them and we shouldn't expect two different fish of the same species to respond the same .

 

[lovely_trequart]

How often are you feeding? I'm fairly certain I caused the slow death of several fish by underfeeding when I first started.