REAGENT or RESOURCE	SOURCE	IDENTIFIER
Antibodies
Anti-Natriuretic peptides A antibody [EPR20247]	Abcam	Cat#ab209232
anti-cTnT polyclonal (rabbit)	Abcam	Cat#ab45932; RRID:AB_956386
anti-KCNQ1 polyclonal (rabbit)	Abcam	Cat#ab181798
Chemicals, peptides, and recombinant proteins
Tricaine/MS-222	Sigma-Aldrich	Cat#A5040
Methyl cellulose	Sigma-Aldrich	Cat#M0512
Cas9 protein	IDT	Cat#1081058
HMR-1556	Sigma-Aldrich	Cat#SML2354
Critical commercial assays
Hybridization Chain Reaction Probes and Hairpins Version 3	Molecular Instruments	N/A
DreamTaq Hot Start Green PCR Master Mix	Thermo Scientific	Cat#K9022
LA Taq DNA polymerase	TaKaRa	Cat#RR042B
RNeasy Mini Kit	QIAGEN	Cat#74104
SuperScript IV VILO Master Mix	Invitrogen	Cat#11756050
KiCqStart SYBR Green qPCR ReadyMix	Sigma-Aldrich	Cat#KCQS00
iTaq Universal SYBR Green Supermix	Bio-Rad	Cat#1725121
Deposited data
Adult zebrafish heart proteomics data	ProteomeXchange Consortium	PRIDE Identifier: PXD038300
Experimental models: Organisms/strains
Zebrafish: AB wild-type	ZIRC	Cat#ZL1
Zebrafish: Tg(cmlc2:eGFP)	Tsai et al., 200356	ZDB-TGCONSTRCT-070117-164
Zebrafish: Tg(gata1:dsRed)	Zon et al., 200357	ZDB-TGCONSTRCT-070117-38
Oligonucleotides
crRNA for ttna gRNA: AAGCTCAGTACGTTCTTCAC	IDT	N/A
TracrRNA for ttna gRNA	IDT	N/A
Forward primer for ttnaΔ9 genotyping: GCCTTCCTTCCACATTTATTTTCCA	IDT	N/A
Reverse primer for ttnaΔ9 genotyping: CAGGCTATCAGTGCCCATCA	IDT	N/A
Translation-blocking morpholino against nppa: TCAGAATTAGTCCCCCGGCCATCTC	Becker et al.58	N/A
Translation-blocking morpholino against nppb: TGTGAAGCGATTTCATGTCTCCTGA	Becker et al.58	N/A
Control morpholino: CCTCTTACCTCAGTTACAATTTATA	Gene Tools	SKU:PCO-StandardControl-100
gRNA for generating Δ9 deletion in TTN: TGTTTCAGATGTTGCAATCA	IDT	N/A
HDR template for generating Δ9 deletion in TTN: CAATCATTGCACGCTTACTAATATCCTGGCCTT	IDT	N/A
Primers/Probes for qPCR	IDT	See Table S2
Software and algorithms
Imaris	Bitplane	https://imaris.oxinst.com/
GraphPad Prism	GraphPad	https://www.graphpad.com/
CHOPCHOP	Labun et al.59	https://chopchop.cbu.uib.no/
AMT Imaging software V.7.0.1	Advanced Microscopy Techniques Corp.	https://www.amtimaging.com/
Spinnaker SDK software	FLIR	https://www.flir.com/products/spinnaker-sdk/
Fiji/ImageJ	Schindelin et al.60	https://fiji.sc/
Zen software	Zeiss	https://www.zeiss.com/microscopy/en/products/software/zeiss-zen.html
LabScribe ECG recording software	iWorx	https://iworx.com/labscribe/?v=7516fd43adaa
VisualSonics Echocardiogram Software	Fujifilm	VevoCQ
OpenCV	Open Source Computer Vision Library	https://opencv.org
scikit-learn	Scikit-learn	https://scikit-learn.org
pCLAMP 10	Moleculardevices	https://support.moleculardevices.com/s/article/Axon-pCLAMP-10-Electrophysiology-Data-Acquisition-Analysis-Software-Download-Page
Other
High-speed camera	FLIR	BFS-U3-17S7M-C
Zebrafish ECG recording system	iWorx	ZS-200
Vevo2100 Imaging System	Fujifilm	Vevo2100
MX550S Ultrasound Transducer	Fujifilm	MX550S
Axopatch Amplifier	Moleculardevices	200B
PatchStar Micromanipulator	Scientifica	https://www.scientifica.uk.com/products/scientifica-patchstar-micromanipulator
Nikon Eclipse	Nikon	Ti
Axon Digidata	Moleculardevices	1550A