Fish Dying for Unknown Reason in Established tank - Help! - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 24 Old 08-11-2011, 08:07 PM Thread Starter
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Fish Dying for Unknown Reason in Established tank - Help!


Over the past month, I have much of my tank die, the latest death was today. It started with a Red Wag, that I euthanized because I suspected it had tuberculosis over a month ago. Soon after, another red wag died. From that point to today, a Rasbora, and Black Phantom Tetra being the latest, and an Angelfish have died, none of which showed any signs of disease.

Somebody please help!!! I don't know what to do.

1. Size of tank?
30 Gal

2. Water parameters
a. Ammonia? 0
b. Nitrite? 0
c. Nitrate? 15
d. pH, KH and GH? Unknown
e. Test kit? API

3. Temperature?
78 F

4. FW (fresh water) or BW (brackish)?

5. How long the aquarium has been set up?
1 Year

6. What fish do you have? How many are in your tank? How big are they? How long have you had them?
9 Fish.
1 Angelfish - 3 inches
3 Rasboras - Almost an inch each
3 Black Phantom Tetras - Just over an inch each
1 Red Wag Platys - 1 Inch
1 Algae Eater - 2 inches

Dead Fish
2 Red Wags - 1 inch - 6 months
1 Rasbora - 1 inch - 1 year
1 Angelfish - 4 inches - 1 year
1 Black Phantom Tetra

7. Were the fish placed under quarantine period (minus the first batch from the point wherein the tank is ready to accommodate the inhabitants)?
No (Found dead)

8. a. Any live plants? Fake plants?
b. Sand, gravel, barebottom?
c. Rocks, woods, fancy decors? Any hollow decors?
Fake wood and some hollow decor.

9. a. Filtration?
Top Fin 30

10. a. Lighting schedule? What lights are used? 12 hours on-12 hours off
b. Any sunlight exposure? How long? Very small, if any.

11. a. Water change schedule? About 20% every week.
b. Volume of water changed? Around 7 Gallons
c. Well water, tap water, RO water? Tap Water
d. Water conditioner used? Stress Coat
e. Frequency of gravel/sand (if any) vacuumed? Vacuumed almost every water change.

12. Foods? Omega One
How often are they fed? Once a Day

13. a. Any abnormal signs/symptoms?

The first red wag - Curved Spine, Lying on Ground, Not swimming, Torn Tail Fins, It looks like he has a small white spot right infront of his tail fin, but it is hard to get a good view of him.
All other fish looked normal

b. Appearance of poop? Unknown
c. Appearance of gills? Normal

14. a. Have you treated your fish ahead of diagnosis? No
b. What meds were used?

15. Insert photos of fish in question and full tank shot if necessary.
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post #2 of 24 Old 08-11-2011, 10:40 PM
Well I'm thinking your PH and hardness is going to be at least part of the problem. You'll have to find this out. Platys like harder water with a higher PH, Angelfish like softer water with a lower PH.

I would question that your fish had Tuberculosis. More likely it was attacked. 30g isn't really big enough for Angels either, also them and the rasboras should be in larger groups. Angels with 5+ and Rasbora with 6+, same goes for the Black Phantom Tetras, they also like softer water with a lower PH. All these "little" things very possible added up and stressed out your fish and after time as they got bigger they lashed out.

Also any idea what kind of fish your algae eater is?
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post #3 of 24 Old 08-12-2011, 08:20 AM
you have fake plants no need for so much lighting.most of the fish are from peat stained water systems they prefer subdued lighting and soft water.platies like ladayen said need a little salt aka hard water.... try adding active carbon to the filter if possible(just in case the water goes off during wc as you do them often) ... as ladayen said it could be aggression thats the problem and i tend to agree.are you using test strips or liquid api testers?

the number of rasboras are also way off their comfort the black Phantom Tetras can grow to 2 inches or more and having 6 in there with the rest could be a little the angel could nip at it's fins causing stress and infections.

i would suggest re-homing the platy, getting 3 more rasboras would make it less stressful for them but i'm afraid once the angel is grown and theres not much place to hide they might get eaten.

test your water to see if it's hard or soft. if you do re-home the platy you can add peat or add ro water to top up your tank during wc to make it soft for the rest of your fishes.

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4x1.5x1.5 planted tetras,harlequins,
otto,WMM,2 types of celebes rainbows,rcs,amano, bamboo,red ramhorns,MTS
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3x1.5x1.5 russel's lion,blue cleaner,sixline and leopard wrasse,maroon clown pair,green chromis,scorpion,tiger cowrie,turbo,lyretail anthias,jewel,anemone,star polyp,marbled and giant green mushi,zoa
2x1x1 nano sw shrimps
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post #4 of 24 Old 08-12-2011, 10:06 AM
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I agree, you would be surprised at how much stress the Angel alone is putting on your other fish. Fish death with NO signs is usually stress related, even though they say stress leads to sick fish that pick up things like Ick, etc,. I have mixed fish in the past and not followed the ideal conditions of grouping called for and lost many of fish due to it. Be careful what you are mixing as even though it's pleasing to the eyes it's not necessarily healthy for the fish.
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post #5 of 24 Old 08-12-2011, 11:28 AM
Sometimes tap water will have/make subtle changes in its pH or hardness that you won't know about - it doesn't really matter to humans, but if that's the water you fill your tank with then it can make a big difference to your fish. You should have a pH test kit for your tank, especially since you are able to test for other dangerous levels (ammonia, nitrate, nitrite). There have been a couple times after I do significant water changes that I test my pH and it is WAY off from what it normally is. It's a huge stress on your fish, and worth being able to catch early.

I also wasn't aware that Stress Coat was really an everyday water conditioner on its own, I thought it was more of an additive on top of a water conditioner? Since no one else has commented on this, I imagine I'm probably wrong.
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post #6 of 24 Old 08-12-2011, 12:23 PM
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Previous responses have all included good suggestions for the problem(s). [By the way, Stress Coat is a water conditioner, so that's OK.]

Angelfish can be very aggressive. And being a shoaling fish, they naturally expect to be in a group. Scientific study now shows that shoaling fish maintained in too small a group (5 was the number used, and angelfish were in the study) show a heightened aggressiveness to all other fish. This is possibly the major issue. You have angelfish, tetra and rasbora, all of which need to be in groups of 5-6 or more, space permitting. But understand that some angelfish will still be nasty, they are cichlids and this is in their genes, though some fish display it more than others, and as I said it can be induced by conditions (small or no group, small tank, unsuitable water parameters/conditions).

Which brings me to the water parameters. You must know your tap water hardness and pH, and then monitor the pH of the tank. Any change in tank pH can be a clue to trouble; same goes for nitrates. These two are about the only tests you need to do somewhat periodically, assuming the tank is OK with no problems. When problems arise, other tests as you've done are also necessary.

You can find out the tap water hardness and pH from your water supply people, many now have a website with data posted. And an API pH test kit for the tank is a good investment. Find out the tap water pH first so you will know which range kit, there is a high range, normal range and some make a low range; yours will likely be the normal.


Byron Hosking, BMus, MA
Vancouver, BC, Canada

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian. [unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]
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post #7 of 24 Old 08-13-2011, 07:57 PM Thread Starter
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Thank you all for the replies. I know that I need more Rasbora's and Tetras, I was planning on getting more but then fish started dying. As for agression, I was slightly misinformed when starting the tank, but I have only seen agression about 4 or 5 times between the 2 angelfish, and never from the angelfish towards other, smaller fish (The angelfish that died was much larger than the other one in the tank, so I doubt that the current angelfish killed the other).

The PH of the tank is bout 7.0 and the hardness is around 75, not exact.

Maybe I was wrong, but I thought fish that were too stressed out showed signs (not eating, disease, breathing problems) . The fish that died were fine one day, then I would wake up the next day and they would be floating.

Note: The angelfish was in an extremely awkward position when I found him dead. He was halfway into a small rock cave, that he would never have been able to fit into. I think this might have been how he died.

Here is a picture of the first red wag that died. No other fish looked like this though.

All fish look normal in the tank right now.
Attached Images
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post #8 of 24 Old 08-13-2011, 08:28 PM
It sounds like your description of the dead angel is that is exactly what happend. The smaller one chased it and it tried to find a way to escape. It couldn't fit and the other one beat it to death.

Still wondering what your algae eater is. If it's a chinese algae eater that could explain alot.
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post #9 of 24 Old 08-13-2011, 09:15 PM Thread Starter
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The Angelfish beating each other to death sounds way out of touch. By agression I meant they would just nip at each other, never chasing, mostly during feeding time.

The algae eater would be my guess actually. It was listed as "common algae eater" at petsmart. Has anyone else seen it at petsmart and recognized it as a Chinese Algae eater?

Does the chinese algae eater come in different colours? The one I have has a similar pattern on its scales, but it is a different colour.
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post #10 of 24 Old 08-13-2011, 09:21 PM
what does it's mouth look like? is it a sucker mouth or a normal mouth?
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